Left Wing is a term that refers to a broad array of political beliefs held by Liberals, Social Democrats, Democratic Socialists, and Communists to name just a few, for those who need to understand everything in terms of relative spacial reasoning. The left wing of the political spectrum encompasses, to varying degrees based on the position of the ideology on the left wing, the belief that all people are Equal and should be treated as such.
Origins of the terms
It's generally held that the application of the terms "left" and "right" in politics date to the French Revolution. Monarchists and supporters of the tradition of privilege were seated on the "right" of the assembly, and republicans (lower case "r", the US Republican party supports traditional privilege), democrats, liberals, and others were seated on the "left". Application of the term in American politics came much later. Use of the term was somewhat pejorative in the original French, and continues to be in English (except for people who are proudly left wing). The term continues to differentiate those who believe in hereditary privilege and tradition of privilege from those who do not.