In the US this term is associated with the South, and especially with former slaves who after emancipation somehow kept doing the same jobs they had been doing before the civil war. (Though there were also many poor white sharecroppers in the South)

Sharecropping is a common practice in any poor agricultural area. Basically, farmers who don't own their own land rent land from a land owner in exchange for a percentage of the crops raised.

The problem is that the percentage of crops paid in rent keeps going up and up (and what are you going to do about it?), as does the cost of planting, especially when you can only buy seeds and equipment from your landlord (buy from someone else and he'll kick you off the land). If you try to leave he'll throw you in jail for running out on a debt. See also: wage slave