Elyssa Maxx Goodman in the Good Men Project:
In reality, men have been wearing dresses for thousands of years. There’s even an early reference to cross-dressing in the Old Testament. True drag, though, was borne of the stage, when women were not allowed to perform so men took their places in any ridiculous frippery necessary to display some semblance of feminine qualities. Shakespeare was said to use the phrases “enter Dressed Resembling a Girl” or “enter Dressed As Girl” in his plays as notes for male actors, which later evolved into “drag.”
Being a drag queen, however, is different from simply doing drag. A drag queen is primarily a homosexual male who dresses in women’s clothing to entertain. Some sing, some dance, some do stand-up comedy. But a male in drag is not necessarily a drag queen—Milton Berle, Flip Wilson, and even Adam Sandler are all heterosexual males who have donned female attire for comedic effect, but did not do it as a career, as a drag queen does.
For a long time, drag was relegated to gay culture, but in the 1970s with gay liberation movement and the popularization of glam rock icons in outlandish makeup and gender-bendy costumes like David Bowie’s Ziggy Stardust, it experienced a move to the surface.
More here.