This was triggered because of a confrontation between the police and gay folk in a bar from the “Stonewall Inn”, in Greenwich village (NY) in June 1969.
Before this, lesbian, gay, bisexual, and transgendered community had generally no broadcast in their orientation.
From this moment on the community was inspired to take political activism. The first Gay Pride parade was then Saturday, 27 June 1970 by the Chicago Gay Liberation.
Gay Pride parades have very colorful floats, and you can find a lot of people in costumes accompanied by signs claiming equality.