According to the Wikipedia, Canadian teenager Brittany McMillan promulgated the observance of a new commemoration called “Spirit Day,” the first observance of which took place on October 20, 2010, in which people wear the color purple to show support for LGBT young people who are victims of bullying. Promoted by GLAAD or the Gay & Lesbian Alliance Against Defamation, many Hollywood celebrities wore purple on this day to show their support of this cause, and many websites added a prominent purple shade to their design.
The name, Spirit Day comes from the purple stripe of the Rainbow Flag, defined by Gilbert Baker, creator of that flag, as ‘representing “spirit”‘.
The observance was inaugurated in response to a rash of widely-publicized bullying-related suicides of gay school students in 2010, including that of Tyler Clementi.
Over 1.6 million Facebook users signed up for the event globally.