This chapter examines the basic features of socialism and communism. Socialism is a complex ideology with numerous variants that are often strongly opposed to each other on one or more central questions or issues. Variants of socialism have converged with other classical ideologies (such as liberalism) in their beliefs and values, yet other variants have remained vehemently opposed to much within liberalism. The chapter first provides a brief historical background on socialism before discussing the key beliefs, values, and assumptions of socialism. In particular, it looks at socialism's critique of industrial capitalism and its vision of the good society, along with its its conception of human nature, community, and freedom. The chapter proceeds by considering some variants of socialism, especially communism and social democracy, as well as the overlap between socialism and other ideologies like liberalism. Finally, it assesses the historical, contemporary, and future impact of socialism.