Guilds are defined as associations of craftsmen and merchants formed to promote the economic interests of their members as well as to provide protection and mutual aid. As both business and social organizations, guilds were prolific throughout Europe between the eleventh and sixteenth centuries. Guilds were organized so that workers would learn skills from others connected with the guild. Members traditionally advanced through the stages of apprentice, journeyman, and finally masters. Guilds helped to advance and expand the economies of the era by providing education and training for apprentices and by helping journeymen improve their skills. The specialization within a trade provided by the guild structure, along with the training and skills, led to increased productivity, increased wages, and higher standards of living. Guilds became a major source of employment for workers in cities, and guild membership was widespread. Guild leaders, especially those of powerful merchant guilds, frequently also served as local government officials. The decline of guilds after the sixteenth century took place for both economic and religious reasons. Industrialization and the existence of new markets greatly weakened the control of craft guilds. Despite their overall demise, many characteristics of medieval European guilds persist today. Some labor unions use the apprentice/journeyman/master progression of skills and status. Labor unions today perform many of the same functions that guilds did in the past, and like guilds, seek to engage members in mutual cooperation to better the interests of the members.