Segregation is the action of separate parts of a whole, a set, put aside.
Applied to a human, segregation refers to the situation experienced by a person who is voluntarily shelved by others and isolated from their usual social network.
Applied to a group, the segregation is to make him suffer discrimination based on criteria such as ethnicity, skin color (see below), age, sex, level of wealth, manners , religion, etc..
Racial segregation is an organized separation of law or fact between differentiated by the color of the skin (especially between blacks and whites) groups within the same country. The separation can be physical with forbidden places certain groups (restaurant, toilets, school, cinema, housing) or take the form of discrimination (in hiring, renting, civil rights).
The United States in 1896, the Supreme Court allowed states that wished to implement, by law, policies of racial segregation. Legal segregation was gradually abolished after the Second World War, the army in 1948 in public schools in 1954, then in other areas to "Civil Rights Act" of 1964, signed by President Lyndon Johnson outlawing all forms of racial discrimination.