Social Class: The Lower Classes

Townsman
A Freeman that lives in a town. Generally considered higher than a Freeman peasant because they have skills in crafts or are merchants.

Yeoman
Poor farmers that paid rent to work their land. Also known as a Freeman. As a culture gets more civilized the number of yeoman increases as the incentives of wealth for their efforts encourages harder work and greater crop yields than Serfs ever produced. A yeoman that moved to a town would be considered a townsman.

Serfs
Poor farmers that owe a debt to the lord and must work the Lord's land for him (might include mines as well). They can depend upon the Lords protection to an extent. The children of a Serf are also Serfs. After the black plague reduced the population of Serfs in England the peasants revolted resulting in a large number becoming Yeoman. A serf that escaped their lot and made it to a Freetown, and avoided capture for a year would be considered free and be considered a Townsman.

Slaves/Thralls
One that is owned by another. Slavery was common in the Dark Ages but mostly gone by the medieval period. The main difference between Slaves and Serfs is that slaves are protected because they are property, not because the owner has an legal requirement to do so.