A Master of Ceremonies or MC is the host of a staged event or other performance. The MC usually presents performers, speaks to the audience, and generally keeps the show moving.

In the 1970s and 1980s, the term MC (short for "Master of Ceremonies", sometimes misrendered emcee) was generally associated, in hip-hop music, with what is now called rapping. MC has also sometimes been reported to stand for "Microphone Controller", but this appears to be a backronym.

Uncertainty over the letters' expansion may be considered evidence for the ubiquitousness of the acronym: the full "Master of Ceremonies" is very rarely (if ever) used in the rap scene. This confusion prompted the hip-hop group A Tribe Called Quest to include this statement on their Midnight Marauders album (1993): "The title 'MC' means 'Master of Ceremonies'. Some people who MC don't know what this term means." Note the use of MC as a verb.

The term originates from the Roman Catholic Church. At a large Catholic church or cathedral, the Master of Ceremonies organizes and rehearses the proceedings and ritual of each mass. He may also have responsibility for the physical security of the place of worship during the liturgy. At major festivals such as Christmas and Easter, when the liturgies are long and complex, the Master of Ceremonies plays a vital role in ensuring that everything runs smoothly.