A sword is a long, edged piece of metal, used as a cutting, thrusting, and clubbing weapon in many civilizations throughout the world. The word sword comes from the Old English sweord, cognate to Old High German swert, Middle Dutch swaert, Old Norse sverð (cf.Danish sværd, Norwegian sverd, Swedish svärd) Old Frisian and Old Saxon swerd and Modern Dutch zwaard and German Schwert, from a Proto-Indo-European root *swer- "to wound, to hurt".
A sword fundamentally consists of a blade and a hilt, typically with one or two edges for striking and cutting, and a point for thrusting. The basic intent and physics of swordsmanship have remained fairly constant through the centuries, but the actual techniques vary among cultures and periods as a result of the differences in blade design and purpose. The names given to many swords in mythology, literature, and history reflect the high prestige of the weapon (see list of swords).
See main article: Bronze Age sword.
Humans have manufactured and used metal bladed weapons from the Bronze Age onwards. The sword developed from the dagger when the construction of longer blades became possible, from the late 3rd millennium BC in the middle-east, first in arsenic copper, then in tin-bronze. The oldest sword-like weapons are found at Arslantepe, Turkey, and date to around 3300 BC. It's however believed that these are longer daggers, and not the first ancestors of swords. Swords longer than 90 cm were rare and not practical during the Bronze Age as this length exceeds the tensile strength of bronze, which means such long swords would bend easily. It was not until the development of stronger alloys such as steel that longswords became practical for combat.
The hilt, either from organic materials or bronze (the latter often highly decorated with spiral patterns, for example), at first simply allowed a firm grip and prevented the hand from slipping onto the blade when executing a thrust or the blade flying out of the hand in a cut. Some of the early swords typically had long and slender shaped blades intended for thrusting. Later swords were broader and were both cutting and thrusting weapons. A typical variant for European swords is the leaf-shaped blade, which was most common in North-West Europe at the end of the Bronze Age, in the UK and Ireland in particular. The Naue Type II Swords which spread from Southern Europe into the Mediterranean, have been linked by Robert Drews with the Late Bronze Age collapse.
Sword production in China is attested from the Bronze Age Shang Dynasty. The technology for bronze swords reached its high point during the Warring States period and Qin Dynasty. Amongst the Warring States period swords, some unique technologies were used, such as casting high tin edges over softer, lower tin cores, or the application of diamond shaped patterns on the blade (see sword of Goujian). Also unique for Chinese bronzes is the consistent use of high tin bronze (17-21% tin) which is very hard and breaks if stressed too far, whereas other cultures preferred lower tin bronze (usually 10%), which bends if stressed too far. Although iron swords were made alongside bronze, it wasn't until the early Han period that iron completely replaced bronze.
The earliest available Bronze age swords of copper discovered from the Harappan sites date back to 2300 BC. Swords have been recovered in archaeological findings throughout the Ganges-Jamuna Doab region of India, consisting of bronze but more commonly copper. Diverse specimens have been discovered in Fatehgarh, where there are several varieties of hilt. These swords have been variously dated to periods between 1700-1400 BCE, but were probably used more extensively during the opening centuries of the 1st millennium BCE.
Not every sword company that used bronze also developed swords. For example, the steppe tribes preferred short daggers (the akinakes). In South America, bronze was used by the Incas, and although the concept of the sword was known in the form of wooden swords with stone edges (the macahuitl), they did not develop bronze swords.
See main article: Iron Age sword and Migration period sword. Iron swords became increasingly common from the 13th century BC. The Hittites, the Mycenaean Greeks, and the Proto-Celtic Hallstatt culture (8th century BC) figured among the early users of iron swords. Iron has the advantage of mass-production due to the wider availability of the raw material. Early iron swords were not comparable to later steel blades. The iron was not quench-hardened although often containing sufficient carbon, but work-hardened like bronze by hammering. This made them comparable or only slightly better in terms of strength and hardness to bronze swords. They could still bend during use rather than spring back into shape. But the easier production, and the better availability of the raw material for the first time permitted the equipment of entire armies with metal weapons, though Bronze Age Egyptian armies were at times fully equipped with bronze weapons.
By the time of Classical Antiquity and the Parthian and Sassanid Empires in Iran, iron swords were common. The Greek xiphos and the Roman gladius are typical examples of the type, measuring some 60 to 70 cm. The late Roman Empire introduced the longer spatha (the term for its wielder, spatharius, became a court rank in Constantinople), and from this time, the term longsword is applied to swords comparatively long for their respective periods.
Chinese steel swords made their appearance from the 3rd century BCE Qin Dynasty. The Chinese Dao (刀 pinyin dāo) is single-edged, sometimes translated as sabre or broadsword, and the Jian (劍 pinyin jiàn) double-edged.
The Periplus of the Erythraean Sea mentions swords of Indian iron and steel being exported from India to Greece. Sri Lankan and Indian Blades made of Damascus steel also found their way into Persia.
The spatha type remained popular throughout the Migration period and well into the Middle Ages. Vendel Age spathas were decorated with Germanic artwork (not unlike the Germanic bracteates fashioned after Roman coins). The Viking Age saw again a more standardized production, but the basic design remained indebted to the spatha.Around the 10th century, the use of properly quenched hardened and tempered steel started to become much more common than in previous periods. The Frankish Ulfberht blades (the name of the maker inlaid in the blade) were of particularly consistent high quality. Charles the Bald tried to prohibit the export of these swords, as they were used by Vikings in raids against the Franks.
Wootz steel which is also known as Damascus steel was a unique and highly prized steel developed on the Indian subcontinent as early as the 5th century BCE. Its properties were unique due to the special smelting and reworking of the steel creating networks of iron carbides described as a globular cementite in a matrix of pearlite. In Sri Lanka a unique wind furnace was used to produce the steel, the unique design produced better quality steel. This gave the blade a very hard cutting edge and beautiful patterns. For obvious reasons it became a very popular trading material. The use of Damascus steel in swords became extremely popular in the 16th and 17th centuries. 
It was only from the 11th century that Norman swords began to develop the quillons or crossguard. During the Crusades of the 12th to 13th century, this cruciform type of arming sword remained essentially stable, with variations mainly concerning the shape of the pommel. These swords were designed as cutting weapons, although effective points were becoming common to counter improvements in armour.
As steel technology improved, single-edged weapons became popular throughout Asia. Derived from the Chinese Jian or dao, the Korean hwandudaedo are known from the early medieval Three Kingdoms. Production of the Japanese tachi, a precursor to the katana, is recorded from ca. 900 CE (see Japanese sword).
See main article: Longsword and Zweihänder. From around 1300 to 1500, in concert with improved armour, innovative sword designs evolved more and more rapidly. The main transition was the lengthening of the grip, allowing two-handed use, and a longer blade. By 1400, this type of sword, at the time called langes Schwert (longsword) or spadone, was common, and a number of 15th and 16th century Fechtbücher offering instructions on their use survive. Another variant was the specialized armour-piercing swords of the estoc type. The longsword became popular due to its extreme reach and cutting and thrusting abilities. The estoc became popular because of its ability to thrust into the gaps between plates of armor. The grip was sometimes wrapped in wire or coarse animal hide to provide a better grip and to make it harder to knock a sword out of the user's hand.
In the 16th century, the large Doppelhänder (called the Zweihänder today; both German names refer to the use of both hands) concluded the trend of ever-increasing sword sizes (mostly due to the beginning of the decline of plate armor and the advent of firearms), and the early Modern Age saw the return to lighter, one-handed weapons.
The Japanese katana reached the height of its development at about this time. In the 15th and 16th centuries, samurai increasingly found a need for a sword to use in closer quarters, leading to the creation of the modern katana.
The sword in this time period was the most personal weapon, the most prestigious, and the most versatile for close combat, but it came to decline in military use as technology changed warfare. However, it maintained a key role in civilian self-defense.
See main article: Rapier, Backsword, Épée and Sword replica. Some think the rapier evolved from the Spanish espada ropera in the 16th century. The rapier differed from most earlier swords in that it was not a military weapon but a primarily civilian sword. Both the rapier and the Italian schiavona developed the crossguard into a basket-shaped guard for hand protection. During the 17th and 18th centuries, the shorter smallsword became an essential fashion accessory in European countries and the New World, and most wealthy men and military officers carried one. Both the smallsword and the rapier remained popular dueling swords well into the 18th century.
As the wearing of swords fell out of fashion, canes took their place in a gentleman's wardrobe. Some examples of canes—those known as sword canes or swordsticks—incorporate a concealed blade. The French martial art la canne developed to fight with canes and swordsticks and has now evolved into a sport.
Towards the end of its useful life, the sword served more as a weapon of self-defense than for use on the battlefield, and the military importance of swords steadily decreased during the Modern Age. Even as a personal sidearm, the sword began to lose its preeminence in the early 19th century, paralleling the development of reliable handguns.
Swords continued in use, but were increasingly limited to military commissioned officers' and non-commissioned officers' ceremonial uniforms, although most armies retained heavy cavalry until well after World War I. For example, the British Army formally adopted a completely new design of cavalry sword in 1908, almost the last change in British Army weapons before the outbreak of the war. The last units of British heavy cavalry switched to using armoured vehicles as late as 1938. Swords and other dedicated melee weapons were used occasionally by various countries during World War II, but typically as a secondary weapon as they were outclassed by contemporaneous firearms.
The production of replicas of historical swords originates with 19th century historicism. Contemporary replicas can range from cheap factory produced look-alikes to exact recreations of individual artifacts, including an approximation of the historical production methods.
Three types of attacks can be performed with the blade: striking, cutting, and thrusting. The blade can be double-edged or single-edged, the latter often having a secondary "false edge" near the tip. When handling the sword, the long or true edge is the one used for straight cuts or strikes, while the short or false edge is the one used for backhand strikes. Some hilt designs define which edge is the 'long' one, while more symmetrical designs allow the long and short edges to be inverted by turning the sword of one's hand on the hilt.
The blade may have grooves known as fullers for lightening the blade while allowing it to retain its strength and stiffness, similar to the effect produced by a steel I-beam used in construction. The blade may taper more or less sharply towards a point, used for thrusting. The part of the blade between the Center of Percussion (CoP) and the point is called the foible (weak) of the blade, and that between the Center of Balance (CoB) and the hilt is the forte (strong). The section in between the CoP and the CoB is the middle. The ricasso or shoulder identifies a short section of blade immediately forward of the guard that is left completely unsharpened, and can be gripped with a finger to increase tip control. Many swords have no ricasso. On some large weapons, such as the German Zweihänder, a metal cover surrounded the ricasso, and a swordsman might grip it in one hand to wield the weapon more easily in close-quarter combat. The ricasso normally bears the maker's mark. On Japanese blades this mark appears on the tang (part of the blade that extends into the hilt) under the grip.
At the base of the blade, a flap of leather could be attached to a sword's crossguard, the Chappe which serves to protect the mouth of the scabbard and prevent water from entering. It is also called a Rain Guard.
From the 18th century onwards, swords intended for slashing, i.e., with blades ground to a sharpened edge, have been curved with the radius of curvature equal to the distance from the swordman's body at which it was to be used. This allowed the blade to have a sawing effect rather than simply delivering a heavy cut. European swords, intended for use at arm's length, had a radius of curvature of around a meter. Middle Eastern swords, intended for use with the arm bent, had a smaller radius.
The hilt is the collective term of the parts allowing the handling and control of the blade, consisting of the grip, the pommel, and a simple or elaborate guard, which in post-Viking Age swords could consist of only a crossguard (called cruciform hilt or quillons). The pommel, in addition to improving the sword's balance and grip, can also be used as a blunt instrument at close range. It may also have a tassel or sword knot.
The tang consists of the extension of the blade structure through the hilt.
Common accessories to the sword include the scabbard, as well as the sword belt.
Swords can fall into categories of varying scope. The main distinguishing characteristics include blade shape (cross-section, taper, and length), shape and size of hilt and pommel, age, and place of origin.
For any other type than listed below, and even for uses other than as a weapon, see the article Sword-like object.
One strict definition of a sword restricts it to a straight, double-edged bladed weapon designed for both slashing and thrusting. However, general usage of the term remains inconsistent and it has important cultural overtones, so that commentators almost universally recognize the single-edged swords such as Asian weapons (dāo 刀, katana 刀) as "swords", simply because they have a prestige akin to their European counterparts.
In most of Asian countries, sword (jian 劍, ken, pedang) is double-edged straight bladed weapon, while knife or saber (dāo 刀, do, pisau, golok) refer to single-edged one. Thus, a katana should not be translated to samurai sword.
Europeans also frequently refer to their own single-edged weapons as swords—generically backswords, including sabres. Other terms include falchion, scimitar, cutlass, dussack, Messer or mortuary sword. Many of these refer to essentially identical weapons, and the different names may relate to their use in different countries at different times. A machete as a tool resembles such a single-edged sword and serves to cut through thick vegetation, and indeed many of the terms listed above describe weapons that originated as farmers' tools used on the battlefield.
The Scabbard can also be called a sheath.
See main article: Executioner's sword.
Apart from the aforementioned types of symbolic swords, the following individually named swords are noteworthy: