The UK Singles Chart (currently entitled Official Singles Chart) is compiled by the Official Charts Company (OCC), on behalf of the British record industry, listing the top-selling singles in the United Kingdom, based upon physical sales, paid-for downloads and streaming. To be eligible for the chart, a single is currently defined by the Official Charts Company (OCC) as either a 'single bundle' having no more than four tracks and not lasting longer than 25 minutes or one digital audio track not longer than 15 minutes with a minimum sale price of 40 pence. The rules have changed many times as technology has developed, the most notable being the inclusion of digital downloads in 2004 and streaming in 2014.
The full chart is a Top 200, though the OCC website contains the Top 100 only. Some media outlets only list the Top 40 (such as the BBC) or the Top 75 (such as Music Week magazine) of this list. Around 6,500 British retail outlets contribute sales data, as well as most UK online digital-download stores. Unlike charts in the United States, no airplay statistics are used for the official UK Singles Chart. The chart week runs from 00:01 Friday to midnight Thursday, with most UK physical and digital singles being released on Fridays. From 3 August 1969 until 5 July 2015, the chart week ran from 00:01 Sunday to midnight Saturday.
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. Component charts have become an increasingly important way to measure the commercial success of individual songs.