American slang is a major physiognomy of American English and part of the American experience. It is one of the major characteristics that differentiate American English from British English. It makes Standard English more colourful, cleverer and it is a means of self-expression. American slang has a huge number of sources which makes it unique. In my thesis I would like to examine some of these sources. Providing historical background which can help to understand when, where, and why emerged. Explaining who and in which contexts, situations use it. From the different sources I chose jazz, the world of carnivals, baseball, Yiddish, wars, healing, the language of blacks and homosexuals, and Marine Corps. The reason why I chose these areas is that these are considered to be the most important sources, because these slang expressions are not only used by the different subcultures but also infiltrate into everyday conversations.