Many people forget that shields are an important part of armour, mainly because they are carried and not worn. The first shields that were used by knights in England were shaped like a long kite and were brought to the country by the Normans. Over time these became smaller with a flatter top and tapering bottom, resembling the more traditional shield-shaped versions that we are familiar with.
Most shields were created from wood and then covered with leather or a thick parchment (animal skin, not paper) on each side. Many did feature a family coat of arms. Most shields were about 1.5 cm thick but very few specimens from Medieval times remain. Three straps were added to the inside to make it easier to carry. A long strap gave the user the option to carry it over their back when they were not using it in battle.
By the time that plate armour became popular, shields were starting to become redundant as the wearer got similar protection from the suit of armour. Occasionally, those in battle might carry a small wooden shield, known as a buckler as an alternative if they felt that more protection was required.