Music charts also known as the Hit parade, Hot 100 or Top 40 is a method of ranking the most popular music during a given period of time. Primarily a marketing or supermarketing tool like any other sales statistic, they have become a form of popular media culture in their own right The hit parade is the list of songs most popular at any given time. ... The Billboard Hot 100 is the main singles chart used by Billboard magazine. ... Top 40 is a radio format based on frequent repetition of songs from a constantly-updated list of the forty best-selling singles. ...

There are lots of different criteria used in different charts, commonly: sales of records, cassettes and compact discs; amount of radio airplay; and recently number of downloads. Record is also a music album by Montreal-based band Sofa. ... For the meaning of cassette in genetics, see cassette (genetics). ... CD re-directs here; see Cd for other meanings of CD. Image of a compact disc (pencil included for scale) A compact disc (or CD) is an optical disc used to store digital data, originally developed for storing digital audio. ... This article is about the computer terms. ...

Some charts are specific to a particular musical genre and most to a particular geographical location (although download charts are not easily pinned down in this way). The most common period of time covered by a chart is one week with the chart being printed or broadcast at the end of this time. Summary charts for years and decades are then calculated from their component weekly charts. Musical genres are categories which contain music which share a certain style or which have certain elements in common. ...