These are conceptions of state and society that aim to overcome a system that is based on competition and the oppression of the working classes. Overcoming this should lead to an alternative system in which egalitarian ideas are applied not only to political and social issues, but also to economic ones. The term socialism was coined and popularised in the 19th century. Very different movements and groups proclaimed that they were developing their own socialist, just and communal programs, including social reformers, Christians and anarchists. The version of so-called scientific socialism coined by Karl Marx (1818–1883) became particularly prominent. It argued in complex theoretical terms and formulated a version of world history that predicted the coming of communism as the abolition of exploitative conditions, which were characteristic of the capitalist economic systems of that time. The real socialist countries that had existed since 1917, including the GDR, claimed to be a part of this movement.

Since the 19th century, there have been other versions of socialism in history that prioritised either cultural and geopolitical differences (African socialism), other ideological components such as racism and nationalism (national socialism), or other political positions such as participation and anti-bureaucracy (democratic socialism) or adaptations to new times (socialism of the 21st century). For those societies that called themselves socialist between 1917 and 1991, in varying forms and for different lengths of time, certain similarities in their current development are assumed, which are commonly referred to as post-socialism.