A charter is an official, written document intended to serve as evidence of a legally valid agreement between two or more people. It is drawn up according to fixed rules and forms that vary according to the place where the charter originated and the period when it was drawn up.

Charters were written as early as the Roman period. The oldest record in the Netherlands is the (false) charter granted by the German king Otto I to the Limburg abbey of Thorn in 950. The oldest surviving writing document is the wooden writing board of Tolsum, from 28 AD.

Ecclesiastical and secular dignitaries such as popes, bishops, abbots, emperors, kings, dukes and counts were the first to record their agreements in charters. From the twelfth century onwards city councils, knights, priests, citizens and farmers followed.

Initially, charters were written in Latin. From the thirteenth century onwards charters also appeared in the vernacular. The oldest vernacular charter in Dutch Limburg dates from 1294.

In the early Middle Ages charters were written on papyrus. Then they switched to the extremely durable parchment, which was made from the skin of cows, goats, sheep or other animals. In the course of the fourteenth century paper also came to be used.

Medieval writers usually used a quill, but sometimes a reed quill. The ink was iron gallus ink, which consisted of iron salt, tannin from gall nuts, water or wine, and a binder (gum arabic).

Charters are official documents, but there are also forged charters. Especially in the twelfth century many false charters were made. Because a charter could be used to obtain one's rights, it was attractive to fabricate one's own when one had no legal title.

Charters were carefully kept in large chests or cabinets. Many charters were also transcribed in registers, so that we still know many medieval texts that have not been handed down as originals. The fragile parchment charters are now kept in archives equipped with fireproof doors and advanced climate control and alarm systems.

In the early Middle Ages the signature was the most common form used in Western Europe to provide charters with a sign of legal validity. From the end of the ninth century bishops gave evidential value to their charters by means of a seal. In the course of the eleventh century seals became more common. Emperors, bishops and princes were the first to sign, followed by nobles, monasteries and cities. Since the 13th century aldermen and prominent citizens also had their own seals. Most seals were made of beeswax, but the popes used lead, and some high princes and church leaders used gold or silver. A seal was not only the means of ratification of a charter, but also functioned as a status symbol for its owner.