Rounds and catches are a secular type of canon, in which a given melody is imitated at unison in other voices after a given duration, creating a contrapuntal texture.
Rounds are often traditional, rural, pastoral, rustic or folk-like. They can be playful, sometimes literally involving actions of play or games. Catches on the other hand are bawdy, often containing plays of words, double entendre or an adjustment of meaning by arranging the words and silences so that their combination in different voices can lead to vulgar or humorous associations. (Callon, 2002: p. xviii)
From the above, the distinction of the terms canon, round and catch may seem pretty clear, however, there was much conflict in their use over the centuries. In fact, in the past, they were even used interchangeably. An example of this free use of the terminology of the song types would be Playford. In defining catches, he writes: