A shield is a type of personal armor

Personal armor

Personal armor is the whole of protecting clothing, designed to absorb and/or deflect slashing, bludgeoning, and penetrating attacks. They were historically used to protect soldiers, whereas today, they are also used to protect police forces, private citizens and private security guards or...

, meant to intercept attacks, either by stopping projectiles such as arrow

Arrow

An arrow is a shafted projectile that is shot with a bow. It predates recorded history and is common to most cultures.An arrow usually consists of a shaft with an arrowhead attached to the front end, with fletchings and a nock at the other.- History:...

s or redirecting a hit from a sword

Sword

A sword is a bladed weapon used primarily for cutting or thrusting. The precise definition of the term varies with the historical epoch or the geographical region under consideration...

, mace or battle axe

Battle axe

A battle axe is an axe specifically designed for combat. Battle axes were specialized versions of utility axes...

 to the side of the shield-bearer.

Shields vary greatly in size, ranging from large panels that protect the user's entire body to small models (such as the buckler

Buckler

A buckler is a small shield, 15 to 45 cm in diameter, gripped in the fist; it was generally used as a companion weapon in hand-to-hand combat during the Medieval and Renaissance, as its size made it poor protection against missile weapons but useful in deflecting the blow of...

) that were intended for hand-to-hand-combat use. Shields also vary a great deal in thickness; whereas some shields were made of relatively deep, absorbent, wooden planking to protect soldiers from the impact of spear

Spear

A spear is a pole weapon consisting of a shaft, usually of wood, with a pointed head.The head may be simply the sharpened end of the shaft itself, as is the case with bamboo spears, or it may be made of a more durable material fastened to the shaft, such as flint, obsidian, iron, steel or...

s and crossbow

Crossbow

A crossbow is a weapon consisting of a bow mounted on a stock that shoots projectiles, often called bolts or quarrels. The medieval crossbow was called by many names, most of which derived from the word ballista, a torsion engine resembling a crossbow in appearance.Historically, crossbows played a...

 bolts, others were thinner and lighter and designed mainly for deflecting blade strikes.

In prehistory and during the era of the earliest civilizations, shields were made of wood, animal hide, woven reeds or wicker.