A ricercar (also spelled ricercare, Italian pronunciation: [ritr'kare]) is a type of late Renaissance and mostly early Baroque instrumental composition. The term ricercar means to search out, and many ricercars serve a preludial function to "search out" the key or mode of a following piece. A ricercar may explore the permutations of a given motif, and in that regard may follow the piece used as illustration. The term is also used to designate an etude or study that explores a technical device in playing an instrument, or singing.
In its most common contemporary usage, it refers to an early kind of fugue, particularly one of a serious character in which the subject uses long note values. However, the term has a considerably more varied historical usage.
In the sixteenth century, the word ricercar could refer to several types of compositions. Terminology was flexible, even lax then: whether a composer called an instrumental piece a toccata, a canzona, a fantasia, or a ricercar was clearly not a matter of strict taxonomy but a rather arbitrary decision. Yet ricercars fall into two general types: a predominantly homophonic piece, with occasional runs and passagework, not unlike a toccata, found from the late fifteenth to the mid-sixteenth century, after which time this type of piece came to be called a toccata; and from the second half of the sixteenth century onward, a sectional work in which each section begins imitatively, usually in a variation form. The second type of ricercar, the imitative, contrapuntal type, was to prove the more important historically, and eventually developed into the fugue. Marco Dall'Aquila (c.1480-after 1538) was known for polyphonic ricercars.