Feudalism was the military and political system during most of the middle ages. The king would grant land to a lord in exchange for a certain number of knights. The lord would then grant pieces of that land called fiefs to vassals in exchange for ten days of military service. The lord too, would fight if neccesary. Peasants and serfs would work the land for protection and a small porton of the crop. Peasants were free and could do as they chose, whereas the serfs were property of the lord or vassal and recieved no cash payment whatsoever. Both, though, were always very poor.
The land owned by the lord was known as a manor. A manor was a self- sufficient economic unit and consisted of a village, mill or mills, some body of running water, a castle(with moat), serfs huts, church and rectory, fields, a forest of some sort, and a bakehouse among other things.
Monasteries and Convents
Another type of self-sufficient unit was a monastery (also known as an abbey). Here, monks lived simple lives of work and prayer. Along with laboring in the fields, monks worked in the scriptorium, copying manuscripts. Eventually, the role of monasteries was broadened to include the collection of taxes and running of courts, the punishment of criminals, and the making of laws. Monasteries were also the primary centers of learning where Latin was taught and historical manuscripts were preserved. Not only that, but they served as hospitals and inns. Like these monasteries there were convents, which housed nuns.
Guilds
Guilds, which are like present day workers unions, developed around the 11th century a.d. when craftsmen were forced to regulate the increased trade brought on by the crusades. Each guild had its own standards and punishments. Products could only be purchased from someone in the respective guild for his/her product. To become a member of a guild, one must first spend years learning the trade under a master craftsman without a wage for several years. If approved by the guild members, he/she could then move on to the next stage, journeyman. As a journeyman, one could work under a master craftsmen earning a wage, until deemed ready to be a master craftsman. He/she would then present a "masterpiece" to the guildsmen. If the masterpiece was judged sufficient, he/she was then a master craftsman and a full-fledged member of the guild.