A socialist is someone who supports a political or economic philosophy that says society as a whole, rather than private companies, should own or control various goods and services.
The word socialist has become so politicized that it can be hard to define accurately. The original 19th century socialists were Marxists who believed that workers, and society, should have total control of the means of production. This economic philosophy (and the accompanying politics) is known as socialism. Today's socialists hold a wide variety of beliefs, from community ownership of land and businesses to government control of goods and services for the public good, funded through taxation.