The International Day against Homophobia and Transphobia (IDAHO) is celebrated every May 17 because on that day in 1990, homosexuality was removed from the International Classification of Diseases of the World Health Organization.
The month of June was originally celebrated as LGBT Pride month to commemorate the June 1969 Stonewall riots in New York City, which sparked the modern LGBT civil rights movement in the United States.
To see the official website, click here: http://dayagainsthomophobia.org/
