A serf was a person in medieval Europe who was legally bound to live and work on a lord's land. Unlike slaves, serfs weren't considered property that could be bought and sold separately from the land, but they weren't free either. They couldn't leave the manor where they were born without permission, and they had to farm the lord's fields and give him a portion of their harvest.

Think of it this way: a serf was tied to the land like a tree is rooted in one spot. If the lord sold his estate to someone else, the serfs went with it. In exchange for working the land and paying taxes (often in crops or labor), serfs received protection and a small plot where they could grow food for their own families.

The system, called serfdom, was common from roughly 800 to 1500 AD. Serfs formed the backbone of medieval agriculture, doing the hard work of farming that fed everyone from knights to kings.

Serfdom gradually disappeared as cities grew, trade expanded, and new ideas about freedom and individual rights spread across Europe. Today, when someone says they feel like a serf, they mean they feel trapped in endless, unrewarding work with no control over their own life.