Some of the most well-known companies that list hit songs are Billboard and Shazam, which feature extensive coverage of new and popular songs across a variety of genres. Both services use a several sources to identify the popularity of current hits.
Billboard began as a trade magazine in 1894, but rose to prominence when it began covering music in the 1950s. The magazine and website publish lists of new, hit songs by overall popularity as well as by genre, such as rock, country and hip hop. Billboard tracks popularity by radio play, unlike Shazam, which tracks hit songs by their numbers of plays through services such as iTunes and Spotify. Shazam is also well-known for its music identification feature, which can identify the name of a song as well as its artist through an audio sample.