The Billboard charts tabulate the relative weekly popularity of songs or albums in the United States. The results are published in Billboard magazine. The two primary charts – the Hot 100 (top 100 singles) and the Billboard 200 (top 200 albums) – factor in airplay, as well as music sales in all relevant formats.

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 and digital downloads.

All of Billboard's charts use this basic formula. What separates the charts is which stations and stores are used – each musical genre having 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 Billboard's charts. At the time, instead of using SoundScan or 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 Nielsen 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 Billboard's charts use this technology.

Before September 1995, singles were allowed to chart in the week they first went on sale based on airplay points alone. The policy was changed in September 1995 to only allow a single to debut after a full week of sales on combined sales and airplay points. This allowed several tracks to debut at number one.

In December 1998, the policy was further modified to allow tracks to chart on the basis of airplay alone without a commercial release. This change was made to reflect the changing realities of the music business. Previous to this, several substantial radio and MTV hits had not appeared on the Billboard chart at all, because many major labels chose not to release them as standalone singles, hoping their unavailability would spur greater album sales. Not offering a popular song to the public as a single was unheard of before the 1970s. The genres that suffered most at the time were those that increasingly impacted pop culture, including new genres such as trip hop and grunge. Among the many pre-1999 songs that had ended up in this Hot 100 limbo were The Cardigans' "Lovefool", Natalie Imbruglia's "Torn", Goo Goo Dolls' "Iris", OMC's "How Bizarre", Sugar Ray's "Fly" and No Doubt's "Don't Speak".

Starting in 2005, Billboard changed its methodology to allow paid digital downloads from digital music stores such as iTunes to chart with or without the help of radio airplay.

Adverb

weekly (not comparable)

1. Once every week.

   She visits her mother weekly.

2. Every week.

weekly (not comparable)

1. Of or relating to a week.
2. Happening once a week, or every week.

   He's going for his weekly check-up at the hospital.

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