卡农（Canon）是一种音乐谱曲技法，和赋格一样是复调音乐的写作技法之一，也是利用对位法的模仿技法。卡农同时也指以此种技法创作出来的音乐作品，比如巴赫的《五首卡农变奏曲》。

卡农的所有声部虽然都模仿一个声部，但不同高度的声部依一定间隔进入，造成一种此起彼伏，连绵不断的效果，轮唱也是一种卡农。在卡农中，最先出现的旋律是导句，以后模仿的是答句。

根据各声部高度不同的音程差，可分为同度卡农，五度卡农，四度卡农等；根据间隔的时间长短，可分为一小节卡农，两小节卡农等；此外还有伴奏卡农，转位卡农，逆行卡农，反行卡农，摇滚卡农等各种手法。

A round or perpetual canon is a musical composition, a limited type of canon, in which a minimum of three voices sing exactly the same melody at the unison (and may continue repeating it indefinitely), but with each voice beginning at different times so that different parts of the melody coincide in the different voices, but nevertheless fit harmoniously together (Johnson 2001). It is one of the easiest forms of part singing, as only one line of melody need be learned by all parts, and is part of a popular musical tradition. They were particularly favoured in glee clubs, which combined amateur singing with regular drinking (Aldrich 1989, introductory essay, 8–22, especially at 21: "Catch-singing is unthinkable without a supply of liquor to hand..."). The earliest known rounds date from the 12th century.