A cover band (or covers band), is a band that plays mostly or exclusively cover songs. New or unknown bands often find the format marketable for smaller venues, such as pubs, clubs or parks. The bands also perform at private events, for example, weddings and birthday parties and may be known as a wedding band, party band or function band. A band whose covers consist mainly of songs that were chart hits is often called a top 40 band. Some bands, however, start as cover bands, then grow to perform original material. For example, The Rolling Stones released three albums consisting primarily of covers before recording one with their own original material.