Guilds controlled industry and trade in medieval Europe. They provided basic services such as medical care, funeral costs, and cash assistance for families of all members, insured quality and price of all goods, and protected local merchants and craftsmen by limiting competition. Guilds also funded religious and civic functions on important holidays.
This chart shows the basic organization of a craft guild, a guild that controlled a specific industry such as weaving or carpentry. Merchant guilds provided similar functions as craft guilds but did not have the formal training system.
The modern university structure was formed from student guilds in early universities. Modern corporations and labor unions also owe part of their structure to medieval craft guilds.

The masters wrote guild rules, managed the treasury, policed members, and assessed membership applications. In theory masters were determined by merit. In practice they usually selected their children or friends. They also limited the number of workshops in a town, insuring that all masters ran a profitable business.

The expression "journeymen" came from the French word journée, meaning "day" because journeymen were paid wages by the day.

Applications to become a master craftsman had to be approved by the guild leadership. Although skill was important, the guild masters frequently determined applications based on family connections and whether the masters felt they needed another workshop in the town.

The "masterpiece" was some work that demonstrated most or all of the skills used by the craft. Masterpieces were presented to the guild masters and assessed for quality. In some guilds masters provided some type of examination in place of a masterpiece.

A boy's parents placed him in an apprenticeship. At times masters might take boys of any social status as apprentices, except serfs who were bound to their lord and not free to leave. Even this restriction was sometimes ignored if the master chose to overlook a boy's background. Apprenticeship offered a potential way out of poverty for peasants.
At other times the guild leadership restricted the number of apprentices or who could be one if the guild felt there was not enough work to support them.

Although the length of apprenticeship was usually set in advance anywhere from two to nine years, apprenticeships might end early if a master felt the apprentice had learned enough to become a journeyman or was too disobedient to continue the training.