In the 1930s, record companies began issuing collections of 78 rpm records by one performer or of one type of music in specially assembled albums, typically with artwork on the front cover and liner notes on the back or inside cover. Most albums included three or four records, with two sides each, making six or eight tunes per album. When the 12-inch vinyl LP era began in 1949, the single record often had the same or similar number of tunes as a typical album of 78s, and was still often referred to as an "album".