Hard Rock Albums

The Billboard charts tabulate the relative weekly popularity of singles or albums in the United States and elsewhere. The results are published in Billboard magazine. Billboard biz, the online extension of the Billboard charts, provides additional weekly charts. There are also Year End charts. The charts may be dedicated to specific genre such as R&B, country or rock, or they may cover all genres. The charts can be ranked according to sales, streams or airplay, and for main song charts such as the Hot 100 song chart, all three pools of data are used to compiled the charts. For the Billboard 200 album chart, streams and track sales are included in addition to album sales.

The weekly sales and streams charts are monitored on a Friday to Thursday cycle since July 2015, previously it was on a Monday to Sunday cycle. Radio airplay song charts however follows the Monday to Sunday cycle (previously Wednesday to Tuesday). The charts are updated the following Tuesday, but dated the Saturday a further week (i.e. 11 days) later.

On January 4, 1936, Billboard magazine published its first music hit parade. The first Music Popularity Chart was calculated in July 1940. A variety of song charts followed, which were eventually consolidated into the Hot 100 by mid-1958. The Hot 100 currently combines single sales, radio airplay, digital downloads, and streaming activity (including data from YouTube and other video sites). All of the Billboard charts use this basic formula. What separates the charts is which stations and stores are used; each musical genre has a core audience or retail group. Each genre's department at Billboard is headed up by a chart manager, who makes these determinations.

For many years, a song had to be commercially available as a single to be considered for any of the Billboard charts. At the time, instead of using Nielsen SoundScan or Nielsen Broadcast Data Systems (BDS), Billboard obtained its data from manual reports filled out by radio stations and stores. According to the 50th Anniversary issue of Billboard, prior to the official implementation of SoundScan tracking in November 1991, many radio stations and retail stores removed songs from their manual reports after the associated record labels stopped promoting a particular single. Thus songs fell quickly after peaking and had shorter chart lives. In 1990, the country singles chart was the first chart to use SoundScan and BDS. They were followed by the Hot 100 and the R&B chart in 1991. Today, all of the Billboard charts use this technology.

...
Wikipedia