SO or so may refer to:
The Soviet Union, officially the Union of Soviet Socialist Republics (USSR), was a federal sovereign state in northern Eurasia that existed from 1922 to 1991. Nominally a union of multiple national Soviet republics, its government and economy were highly centralized.
South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by 2,798 kilometres (1,739 mi) of coastline of Southern Africa stretching along the South Atlantic and Indian Oceans; to the north by the neighbouring countries of Namibia, Botswana, and Zimbabwe; and to the east and northeast by Mozambique and Eswatini (Swaziland); and it surrounds the enclaved country of Lesotho.
The Solar System is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly.
Southeast Asia is a subregion of Asia, consisting of the countries that are geographically south of China and Japan, east of India, west of Papua New Guinea, and north of Australia.
South America is a continent in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere.
Social media are interactive computer-mediated technologies that facilitate the creation and sharing of information, ideas, career interests and other forms of expression via virtual communities and networks.
The Socialist Federal Republic of Yugoslavia (SFRY), also known as SFR Yugoslavia or simply Yugoslavia, was a country located in central and Southeastern Europe that existed from its foundation in the aftermath of World War II until its dissolution in 1992 amid the Yugoslav Wars.