The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family. The word potato may refer to the plant itself as well. In the region of the Andes, there are some other closely related cultivated potato species. Potatoes are the world's fourth largest food crop, following rice, wheat, and corn.
Wild potato species occur from the United States to Uruguay and Chile. Genetic testing of the wide variety of cultivars and wild species suggest that the potato has a single origin in the area of southern Peru, from a species in the Solanum brevicaule complex. However, although Peru is essentially the birthplace of the potato, today over 99% of all cultivated potatoes worldwide are descendants of a subspecies indigenous to south-central Chile. Based on historical records, local agriculturalists, and DNA analyses, the most widely cultivated variety worldwide, Solanum tuberosum tuberosum, is believed to be indigenous to Chiloé Archipelago where it was cultivated as long as 10,000 years ago. 
The potato was introduced to Europe in 1536, and subsequently by European mariners to territories and ports throughout the world. Thousands of varieties persist in the Andes, where over 100 varieties might be found in a single valley, and a dozen or more might be maintained by a single agricultural household. Once established in Europe, the potato soon became an important food staple and field crop. But lack of genetic diversity, due to the fact that very few varieties were initially introduced, left the crop vulnerable to disease. In 1845, a plant disease known as late blight, caused by the fungus-like oomycete Phytophthora infestans, spread rapidly through the poorer communities of western Ireland, resulting in the crop failures that led to the Great Irish Famine.
The annual diet of an average global citizen in the first decade of the twenty-first century would include about 33 kilograms (or 73 lbs.) of potato. However, the local importance of potato is extremely variable and rapidly changing. The potato remains an essential crop in Europe (especially eastern and central Europe), where per capita production is still the highest in the world, but the most rapid expansion of potato over the past few decades has occurred in southern and eastern Asia. China is now the world's largest potato producing country, and nearly a third of the world's potatoes are harvested in China and India. More generally, the geographic shift of potato production has been away from wealthier countries toward lower-income areas of the world.
The English word potato comes from Spanish patata (the name used in Spain). The Spanish Royal Academy says the Spanish word is a compound of the Taino batata (sweet potato) and the Quechua papa (potato). This probably indicates that originally, the potato was regarded as a type of sweet potato rather than the other way around, despite the fact that there is actually no close relationship between the two plants at all. Potatoes are occasionally referred to as "Irish potatoes" in the English speaking world, to distinguish them from sweet potatoes. In certain dialects of English, particularly in North America, the words taters, potaters, and tatoes are sometimes used. In some dialects of English spoken in Ireland, potatoes are called praties, which, presumably, comes from prátaí, the plural form of the Irish word for potato, práta.
Romanian cartof, Ukrainian картопля (kartóplja), Bulgarian картоф (kartof), Russian картофель (kartofel), German Kartoffel, Danish kartoffel, Icelandic kartafla (or jarðepli, see below), Latvian kartupelis, and Estonian kartul (as well as many other similar names in various languages) all derive from the archaic Italian word tartufoli, which was given to potato because of its similarity to truffles (Italian: tartufo). However, the current Italian term for the potato is patata.
The French refer to the potato as pomme de terre. Pomme translates into "apple", thus pomme de terre means literally "earth apple". Other European translations include aardappel in Dutch, jarðepli in Icelandic (or kartafla, see above), תפוח אדמה in Hebrew (often written just as תפוד), Erdapfel in Austrian German, سیبزمینی sib zamini in Persian. It is called ziemniaki (or kartofle in some regions) in Polish, and zemiak in Slovak, both simply from the word for "ground".
In Marathi and Gujarati, the potato is called bataka or batata, while in most other South Asian languages, (e.g. Hindi, Nepali, Bengali) it is called alu.Different names for the potato developed in China's various regions. The most widely used names in Standard Mandarin are "horse-bell yam" (Simplified Chinese: 马铃薯; Pinyin: mǎlíngshǔ), "earth bean" (Simplified Chinese: 土豆; Pinyin: tǔdòu), and "foreign taro" (Simplified Chinese: 洋芋; Pinyin: yángyù).
The Malay/Indonesian name is kentang.
Potato plants are herbaceous perennials that grow about 60 cm high, depending on variety, the culms dying back after flowering. They bear white, pink, red, blue or purple flowers with yellow stamens resembling those of other Solanaceous species such as tomato and aubergine. The tubers of varieties with white flowers generally have white skins, while those of varieties with colored flowers tend to have pinkish skins. Potatoes are cross-pollinated mostly by insects, including bumblebees that carry pollen from other potato plants, but a substantial amount of self-fertilizing occurs as well. Tubers form in response to decreasing day length, although this tendency has been minimized in commercial varieties. After potato plants flower, some varieties will produce small green fruits that resemble green cherry tomatoes, each containing up to 300 true seeds. Potato fruit contains large amounts of the toxic alkaloid solanine, and is therefore unsuitable for consumption.
All new potato varieties are grown from seeds, also called "true seed" or "botanical seed" to distinguish it from seed tubers. By finely chopping the fruit and soaking it in water, the seeds will separate from the flesh by sinking to the bottom after about a day (the remnants of the fruit will float). Any potato variety can also be propagated vegetatively by planting tubers, pieces of tubers, cut to include at least one or two eyes, or also by cuttings, a practice used in greenhouses for the production of healthy seed tubers. Some commercial potato varieties do not produce seeds at all (they bear imperfect flowers) and are propagated only from tuber pieces. Confusingly, these tubers or tuber pieces are called "seed potatoes".
The potatoes cultivated in the Andes are not all the same species. However, the major species grown worldwide is Solanum tuberosum (a tetraploid with 48 chromosomes). Modern varieties of this species are the most widely cultivated worldwide. There are also four diploid species (with 24 chromosomes): Solanum stenotomum, Solanum phureja, Solanum goniocalyx and Solanum ajanhuiri. There are two triploid species (with 36 chromosomes): Solanum chaucha and Solanum juzepczukii. There is one pentaploid cultivated species (with 60 chromosomes): Solanum curtilobum.
There are two major subspecies of Solanum tuberosum: andigena, or Andean; and tuberosum, or Chilean. The Andean potato is adapted to the short-day conditions prevalent in the mountainous equatorial and tropical regions where it originated. The Chilean potato is adapted to the long-day conditions prevalent in the higher latitude region of southern Chile, especially on Chiloé Island where it is thought to have originated.
There are about five thousand potato varieties world wide. Three thousand of them are found in the Andes alone, mainly in Peru, Bolivia, Ecuador, Chile and Colombia. They belong to eight or nine species, depending on the taxonomic school. Apart from the five thousand cultivated varieties, there are about 200 wild species and subspecies, many of which can be cross-bred with cultivated varieties, which has been done repeatedly to transfer resistances to certain pests and diseases from the gene pool of wild species to the gene pool of cultivated potato species. Genetically modified varieties have met public resistance in the United States and in the European Union. 
Most modern potatoes grown in North America arrived through European settlement and not independently from the South American sources. However, at least one wild potato species, Solanum fendleri, is found as far north as Texas and used in breeding for resistance to a nematode species attacking cultivated potatoes. A secondary center of genetic variability of the potato is Mexico, where important wild species are found that have been used extensively in modern breeding, such as the hexaploid Solanum demissum, as a source of resistance to the devastating late blight disease. Another plant native to this region, Solanum bulbocastanum, a close relative of the potato, has been used to genetically engineer the potato to effectively resist potato blight.
Although it was initially feared to be poisonous, the potato became an important staple crop in northern Europe. Famines in the early 1770s contributed to its acceptance, as did government policies in several European countries and climate change during the Little Ice Age, when traditional crops in this region did not produce as reliably as before.  At times when and where most other crops would fail, potatoes could still typically be relied upon to contribute adequately to food supplies during the colder years. Its yield of Calories per acre (about 9.2 million) is higher than that of maize (7.5 milion), rice (7.4 million), wheat (3 million), or soybean (2.8 million). The potato was not popular in France during this time, and it is believed that some of the infamous famines could have been lessened if French farmers had adopted it. Today, the potato forms an important part of the traditional cuisines of most of Europe. Belarus has the highest consumption of potato per capita with each Belorussian consuming 338 kg in 2005. 
The potato was introduced in the Philippines during the late 16th century, and to Java and China during the 17th century. It was well-established as a crop in India by the late 18th century and in Africa by the mid-20th century.
The United Nations FAO reports that the world production of potatoes in 2006 was 315 million tonnes. The largest producer, China, accounted for one quarter of the global output, followed by Russia and India.
In 2008, several international organizations began to give more emphasis to the potato as a key part of world food production, due to several developing economic problems. They cited the potato's potential for a beneficial role in world food production, owing to its status as a cheap and plentiful crop which can be raised in a wide variety of climates and locales. Due to perishability, only about 5% of the world's potato crop is traded internationally; its minimal presence in world financial markets contributed to its stable pricing during the 2007–2008 world food price crisis. 
In recognition of this importance, the United Nations officially declared the year 2008 as the International Year of the Potato in order to "increase awareness of the importance of the potato as a food in developing nations" and calling the crop a "hidden treasure". This follows the International Rice Year in 2004.
Potatoes are used to brew alcoholic beverages such as vodka and as food for domestic animals; potato starch is used to produce organic chemicals, in the textile industry, and in the manufacture of papers and boards.  Maine companies are exploring the possibilities of using waste potatoes to obtain polylactic acid for use in plastic products; other research projects seek ways to use the starch as a base for biodegradable packaging. 
Nutritionally, potatoes are best known for their carbohydrate content (approximately 26 grams in a medium potato). The predominant form of this carbohydrate is starch. A small but significant portion of this starch is resistant to digestion by enzymes in the stomach and small intestine, and so reaches the large intestine essentially intact. This resistant starch is considered to have similar physiological effects and health benefits as fiber: it provides bulk, offers protection against colon cancer, improves glucose tolerance and insulin sensitivity, lowers plasma cholesterol and triglyceride concentrations, increases satiety, and possibly even reduces fat storage (Cummings et al. 1996; Hylla et al. 1998; Raban et al. 1994). The amount of resistant starch in potatoes depends much on preparation methods. Cooking and then cooling potatoes significantly increases resistant starch. For example, cooked potato starch contains about 7% resistant starch, which increases to about 13% upon cooling (Englyst et al. 1992).
Potatoes contain vitamins and minerals that have been identified as vital to human nutrition. Humans can subsist healthily on a diet of potatoes and milk; the latter supplies Vitamin A and Vitamin D. A medium potato (150g/5.3 oz) with the skin provides 27 mg of vitamin C (45% of the Daily Value (DV)), 620 mg of potassium (18% of DV), 0.2 mg vitamin B6 (10% of DV) and trace amounts of thiamin, riboflavin, folate, niacin, magnesium, phosphorus, iron, and zinc. Moreover, the fiber content of a potato with skin (2 grams) equals that of many whole grain breads, pastas, and cereals. Potatoes also contain an assortment of phytochemicals, such as carotenoids and polyphenols. The notion that "all of the potato's nutrients" are found in the skin is an urban legend. While the skin does contain approximately half of the total dietary fiber, more than 50% of the nutrients are found within the potato itself. The cooking method used can significantly impact the nutrient availability of the potato.
Almost all the protein content of a potato is contained in a thin layer just under its skin. This is evident when the skin of a boiled potato is carefully peeled; it appears as a yellowish film. For maximum utilisation of this small, but valuable dietary source of protein, potatoes should be consumed whole, or peeled after cooking.
Potatoes are often broadly classified as high on the glycemic index (GI) and so are often excluded from the diets of individuals trying to follow a "low GI" eating regimen. In fact, the GI of potatoes can vary considerably depending on type (such as red, russet, white, or Prince Edward), origin (where it was grown), preparation methods (i.e., cooking method, whether it is eaten hot or cold, whether it is mashed or cubed or consumed whole, etc), and with what it is consumed (i.e., the addition of various high fat or high protein toppings) (Fernandes et al. 2006).
Potatoes contain glycoalkaloids, toxic compounds, of which the most prevalent are solanine and chaconine. Solanine is also found in other plants, mainly in the mostly deadly nightshade family, which includes a minority of edible plants including the potato and the tomato, and other typically more dangerous plants like tobacco. This poison affects the nervous system causing weakness and confusion.
These compounds, which protect the plant from its predators, are generally concentrated in its leaves, stems, sprouts, and fruits. Exposure to light, physical damage, and age increase glycoalkaloid content within the tuber; the highest concentrations occur just underneath the skin. Cooking at high temperatures (over 170 °C or 340 °F) partly destroys these. The concentration of glycoalkaloid in wild potatoes suffices to produce toxic effects in humans. Glycoalkaloids may cause headaches, diarrhea, cramps and in severe cases coma and death; however, poisoning from potatoes occurs very rarely. Light exposure causes greening(chlorophyll synthesis), thus giving a visual clue as to areas of the tuber that may have become more toxic; however, this does not provide a definitive guide, as greening and glycoalkaloid accumulation can occur independently of each other. Some varieties of potato contain greater glycoalkaloid concentrations than others; breeders developing new varieties test for this, and sometimes have to discard an otherwise promising cultivar.Breeders try to keep solanine levels below 200 mg/kg (200 ppmw). However, when these commercial varieties turn green, even they can approach concentrations of solanine of 1000 mg/kg (1000 ppmw). In normal potatoes, analysis has shown solanine levels may be as little as 3.5% of the breeders' maximum, with 7–187 mg/kg being found.
The US National Toxicology Program suggests that the average American consumes at most 12.5 mg/day of solanine from potatoes (the toxic dose is actually several times this, depending on body weight). Dr. Douglas L. Holt, the State Extension Specialist for Food Safety at the University of Missouri, notes that no reported cases of potato-source solanine poisoning have occurred in the U.S. in the last 50 years and most cases involved eating green potatoes or drinking potato-leaf tea.
Correct potato husbandry is an arduous task in the best of circumstances. Good ground preparation, harrowing, plowing, and rolling are always needed, along with a little grace from the weather and a good source of water. Three successive plowings, with associated harrowing and rolling, are desirable before planting. Eliminating all root-weeds is desirable in potato cultivation. Potatoes are the most fruitful of the root crops, but much care and consideration is needed to keep them satisfied and fruitful.
Potatoes are generally grown from the eyes of another potato and not from seed. Home gardeners often plant a piece of potato with two or three eyes in a hill of mounded soil. Commercial growers plant potatoes as a row crop using seed tubers, young plants or microtubers and may mound the entire row.
Seed potato crops are 'rogued' in some countries to eliminate diseased plants or those of a different variety from the seed crop.
Potatoes should be harvested before heavy frosts, which damage potatoes in the ground, and even cold weather makes potatoes more susceptible to bruising and possibly later rotting which can quickly ruin a large stored crop.
At harvest time, gardeners usually dig up potatoes with a long-handled, three-prong "grape" (or graip), i.e. a spading fork, or a potato hook which is similar to the graip but its tines are at a 90 degree angle to the handle. In larger plots, the plow can serve as the fastest implement for unearthing potatoes. Commercial harvesting is typically done with large potato harvesters which scoop up the plant and the surrounding earth. This is transported up an apron chain consisting of steel links several feet wide, which separates some of the dirt. The chain deposits into an area where further separation occurs. Different designs use different systems at this point. The most complex designs use vine choppers and shakers, along with a blower system or "Flying Willard" to separate the potatoes from the plant. The result is then usually run past workers who continue to sort out plant material, stones, and rotten potatoes before the potatoes are continuously delivered to a wagon or truck. Further inspection and separation occurs when the potatoes are unloaded from the field vehicles and put into storage.
Potatoes are usually cured after harvest to thicken their skin. Prior to curing, the skin is very thin and delicate. These potatoes are sometimes sold as "New Potatoes" and are particularly flavorful. New potatoes are often harvested by the home gardener or farmer by "grabbling", i.e. pulling out the young tubers by hand while leaving the plant in place. In additions, markets may sometimes present various thin-skinned potato varieties as "new potatoes".
Storage facilities need to be carefully designed to keep the potatoes alive and slow the natural process of decomposition, which involves the breakdown of starch. It is crucial that the storage area is dark, well ventilated and for long-term storage maintained at temperatures near 40°F (4°C). For short-term storage prior to cooking, temperatures of about 45-50°F (7-10°C) are preferred. Temperatures below 40°F (4°C) convert potatoes' starch into sugar, which alters their taste and cooking qualities and leads to higher acrylamide levels in the cooked product, especially in deep-fried dishes.
Under optimum conditions possible in commercial warehouses, potatoes can be stored for up to six months, at homes usually only for several weeks. If potatoes develop green areas or start to sprout, these areas should be trimmed before using.
Potatoes have been bred into many standard or well-known varieties, each of which have particular agricultural or culinary attributes. Varieties are generally categorized into a few main groups—such as russets, reds, whites, yellows (also called Yukons) and purples—based on common characteristics. Popular varieties (cultivars) include:
Genetic research has produced several genetically modified varieties. New Leaf, owned by Monsanto corporation, incorporated genes from Bacillus thuringiensis, which conferred resistance to the Colorado potato beetle; New Leaf Plus and New Leaf Y, approved by US regulatory agencies during the 1990s, also included resistance to viruses. McDonald's, Burger King, Frito-Lay, and Procter & Gamble announced that they would not use genetically modified potatoes, and Monsanto published its intent to discontinue the line in March 2001. The starch content of Amflora, from the German chemical company BASF, has been modified to contain only amylopectin, making it inedible but more useful for industrial purposes; as of 2007, it was close to gaining acceptance in the European Union. On September 22, 2007, Benguet State University (BSU) announced that four potato varieties—Igorota, Solibao, Ganza and one not yet officially named—possess more than 18% dry matter content required by fast-food chains to make crispy and sturdy French fries.
Some horticulturists sell chimeras, made by grafting a tomato plant onto a potato plant, producing both edible tomatoes and potatoes. This practice is not very widespread.
Insects that commonly transmit potato diseases or damage the plants include the Colorado potato beetle, the potato tuber moth, the Green Peach Aphid, the Potato Aphid, Beetleafhoppers, Thrips, and Mites. The potato root nematode is a microscopic worm that thrives on the roots, thus causing the potato plants to wilt. Since its eggs can survive in the soil for several years, crop rotation is recommended.
Potatoes are prepared in many ways: skin-on or peeled, whole or cut up, with seasonings or without. The only requirement involves cooking to break down the starch. Most potato dishes are served hot, but some are first cooked then served cold, notably potato salad and potato chips/crisps.
Common dishes are: mashed potatoes, which are first boiled (usually peeled), and then mashed with milk or yogurt and butter; whole baked potatoes; boiled or steamed potatoes; French-fried potatoes or chips; cut into cubes and roasted; scalloped, diced, or sliced and fried (home fries); grated into small thin strips and fried (hash browns); grated and formed into dumplings, Rösti or potato pancakes. Unlike many foods, potatoes can also be easily cooked in a microwave oven and still retain nearly all of their nutritional value, provided that they are covered in ventilated plastic wrap to prevent moisture from escaping - this method produces a meal very similar to a steamed potato while retaining the appearance of a conventionally baked potato. Potato chunks also commonly appear as a stew ingredient.
For culinary purposes, potato varieties are often described in terms of their waxiness. The distinction arises from the comparative ratio of two potato starch compounds: amylose and amylopectin. Amylose, a long-chain molecule, disintegrates easily when cooked in water, and lends itself to dishes in which the potato is mashed; varieties containing a higher amylopectin content are classified as waxy. Since amylopectin is a more branched and stable molecule, waxy varieties are preferred in dishes where the potato is expected to retain its shape. Potatoes are boiled between 10 and 25 minutes, depending on size and type, to become soft.
Peruvian Cuisine naturally contains the potato as a primary ingredient in many dishes, as around 3,000 varieties of this tuber are grown there. Some of the more famous dishes include Papa a la huancaina, Papa rellena, Ocopa, Carapulcra, Causa and Cau Cau among many others. French-fried potatoes are a typical ingredient in Peruvian stir-fries, including the classic dish Lomo saltado.
In Ecuador the potato, as well as being a staple with most dishes, is featured in the hearty Locro de Papas, a thick soup of potato, squash, and cheese.
In Chile's Chiloé archipelago, potatoes are the main ingredient of many dishes, including milcaos, chapaleles, curanto and chochoca.
In UK potatoes form part of the traditional staple fish and chips. Roast potatoes are commonly served with a Sunday roast. Mashed, potatoes also form a major component of several other traditional dishes such as shepherd's pie, bubble and squeak, champ and the 'mashit tatties' (Scots language) which accompany haggis. The Tattie scone is another popular Scottish dish containing potatoes. They are also often sautéed to accompany a meal. In the UK, new potatoes are typically cooked with mint and served with a little melted butter - Jersey Royal potatoes are the most prized new potatoes, and have their own Protected Designation of Origin.
In Ireland Colcannon is a traditional Irish dish involving mashed potato combined with shredded cabbage and onion. Boxty pancakes are eaten all over Ireland, although associated especially with the north, and in Irish diaspora communities: they are traditionally made with grated potatoes, soaked to loosen the starch and mixed with flour, buttermilk and baking powder. A variant eaten and sold in Lancashire, especially Liverpool, is made with cooked and mashed potatoes.
In Northern and Eastern Europe, especially in Scandinavian countries, Poland, Russia, Belarus and Ukraine, newly harvested, early ripening varieties are considered a special delicacy. Boiled whole and served with dill, these "new potatoes" are traditionally consumed together with Baltic herring. Puddings made from grated potatoes (kugel, kugelis, and potato babka) are popular items of Ashkenazi, Lithuanian, and Belarussian cuisine.
In Western Europe, especially in Belgium, sliced potatoes are fried to create frieten, the original French fried potatoes. Stamppot, a traditional Dutch meal, is based on mashed potatoes mixed with vegetables.
In France the most famous potato dish is the Hachis Parmentier, named after Antoine-Augustin Parmentier, a French pharmacist, nutritionist, and agronomist who, in the late 18th century, was instrumental in the acceptance of the potato as an edible crop in the country. The Pâté aux pommes de terre is a regional potato dish from the central Allier and Limousin regions.
In Italy, potatoes serve to make a type of pasta called gnocchi. Similarly, cooked and mashed potatoes or potato flour can be used in the knödel or dumpling eaten with or added to meat dishes all over central and Eastern Europe, but especially in Bavaria and Luxembourg. Potatoes form one of the main ingredients in many soups such as the vichyssoise and Albanian potato and cabbage soup. In western Norway, komle is popular.
A traditional Canary Islands dish is Canarian wrinkly potatoes or Papas arrugadas. Tortilla de patatas (potato omelete) and Patatas bravas (a dish of fried potatoes in a spicy tomato sauce) are near-universal constituent of Spanish tapas.
In the United States, potatoes have become one of the most widely consumed crops and thus have a variety of preparation methods and condiments. French fries and often hash browns are commonly found in typical American fast-food burger joints and cafeterias. One popular favorite involves a baked potato with cheddar cheese (or sour cream and chives) on top, and in New England "smashed potatoes" (a chunkier variation on mashed potatoes, retaining the peel) have great popularity. Potato flakes are popular as an instant variety of mashed potatoes, which reconstitute into mashed potatoes by adding water, with butter or oil and salt to taste. A regional dish of Central New York, salt potatoes are bite-sized new potatoes boiled in water saturated with salt then served with melted butter. At more formal dinners, a common practice includes taking small red potatoes, slicing them, and roasting them in an iron skillet. Among American Jews, the practice of eating latkes (fried potato pancakes) is common during the festival of Hanukkah.
A traditional Acadian dish from New Brunswick is known as poutine râpée. The Acadian poutine is a ball of grated and mashed potato, salted, sometimes filled with pork in the center, and boiled. The result is a moist ball about the size of a baseball. It is commonly eaten with salt and pepper or brown sugar. It is believed to have originated from the GermanKlöße, prepared by early German settlers who lived among the Acadians.
Poutine, by contrast, is a hearty serving of french fries, fresh cheese curds and hot gravy. Tracing its origins to Quebec in the 1950s, it has become a widespread and popular dish in the francophone Canadian province.
The potato has been an essential crop in the Andes since the pre-Columbian Era. The Moche culture from Northern Peru made ceramics from earth, water, and fire. This pottery was a sacred substance, formed in significant shapes and used to represent important themes. Potatoes are represented anthropomorphically as well as naturally.
During the late 19th century, numerous images of potato harvesting appeared in European art, including the works of Willem Witsen and Anton Mauve. Van Gogh's painting "The Potato Eaters" portrays a family eating potatoes.