Katorga was a system of penal labor in the Russian Empire and the Soviet Union.

Penal labour is a term for various kinds of forced labour that prisoners are required to perform, typically manual labour. The work may be light or hard, depending on the context. Forms of sentence involving penal labour have included involuntary servitude, penal servitude, and imprisonment with hard labour. The term may refer to several related scenarios: labour as a form of punishment, the prison system used as a means to secure labour, and labour as providing occupation for convicts. These scenarios can be applied to those imprisoned for political, religious, war, or other reasons as well as to criminal convicts.