What is considered townhouse compared to an apartment and Condo?

An apartment usually refers to a rental where one person owns the entire building or complex. Condos & townhouses are usually owned individually (i.e. each unit is owned by a different person). Condos generally can be found in buildings with units on at least two levels. Townhouses are more like attached houses where a single unit comprises all the area from top to bottom, usually with at least a little bit of land in front, back or both.