The form of slavery you're referring to is called indentured slavery. In this form of slavery, a person would work off an alleged debt and would be considered a slave until the debt was paid off. This was common in colonial America and was a precursor to chattel slavery, where people were treated as property and passed down from generation to generation. War time slavery refers to the enslavement of captured enemy soldiers or civilians, while physical slavery refers to enslavement based on physical characteristics, such as skin color or ethnicity.