In music performance and music theory, the "downbeat" is the first beat of a measure in music. It is named for the downward stroke of the director or conductor's baton at the start of each measure. This differentiates it from the back beat on the even beats.
In modern music, using common time (4/4), emphasis is usually placed on the third beat or on the back beat, whereas emphasis is rarely put on the downbeat first beat, though a notable exception is in funk where George Clinton dubbed this type of beat "The One".