In the late '50s, singles meant 7-inch, 45-RPM vinyl. By the '80s and '90s, 45s had largely given way to cassette and CD singles. Per Hot 100 rules from the start, songs needed to be released as physical singles in order to be eligible for the chart.
A record label's traditional mission of a single? To infuse radio airwaves with a hit that fans could buy for anywhere from less than a dollar to generally not more than $3.49, in hopes that consumers would be enticed enough to purchase the song's parent album (often priced in the range of seven to under 20 dollars, depending on discounts and track list length).
By the mid-'90s, however, labels were experimenting with not releasing singles for purchase. As early as 1990, Bart Simpson's "Do the Bartman" became an airplay hit, reaching No. 24 on Billboard's Radio Songs chart, while in 1991, Janet Jackson hit No. 5 on Radio Songs with "State of the World" -- but both could be bought only on full albums (The Simpsons Sing the Blues and Janet Jackson's Rhythm Nation 1814, respectively), not on their own. Thus, neither ever appeared in the Hot 100.
(The few earlier examples of classic songs not released to radio, and therefore which never graced the Hot 100, include perhaps the all-time such poster child, Led Zeppelin's "Stairway to Heaven," from 1971's Led Zeppelin IV; Stevie Wonder's No. 23 Adult Contemporary hit "Isn't She Lovely," from 1976's Songs in the Key of Life; and Bon Jovi's "Never Say Goodbye," which reached No. 28 in airplay in 1987, from Slippery When Wet.)
As the '90s progressed, labels' strategy switched from promoting radio hits as (Hot 100-eligible) physical singles to keeping them available on albums only, in order to eliminate consumers' choice to spend lightly on a single, instead forcing them to buy a more expensive LP if they wanted to own a song. (Of course, that’s long before streaming essentially phased out the idea of owning music.)
By 1998, the list of big radio hits not eligible for the Hot 100 due to their lack of commercial availability had swelled. In 1995, The Rembrandts' "I'll Be There for You," which doubled as the theme to NBC's Friends, topped Radio Songs for eight weeks, but had not yet hit the Hot 100. (It later it logged a No. 17 peak once released following its airplay apex, as the B-side to follow-up "This House Is Not a Home.")
Other smashes, promoted to radio but not available for purchase as singles, subsequently scaled Radio Songs but remained absent from the Hot 100. Among them were No. 1s including No Doubt's "Don't Speak" (16 weeks at No. 1 on Radio Songs beginning in December 1996), Will Smith's "Men in Black" (three weeks, 1997) and Sugar Ray's "Fly" (six weeks, 1997).
Thus, the Hot 100 faced an unprecedented challenge: it was no longer the complete barometer of the most popular songs in the U.S. each week -- not when some of the most-heard radio hits were nowhere to be found on the ranking.
(Not cool, man, as a chart-watching Bart Simpson might've said.)
'A NEW HOT 100 REFLECTS CHANGES IN MUSIC BUSINESS'
On Dec. 5, 1998, Billboard implemented a fairly radical rule change to amend that disparity: For the first time, songs did not need to be released as commercial singles to appear on the Hot 100. "The goal is deceptively simple: to reveal the most popular songs in the United States. Period. End of sentence," then-Billboard director of charts Geoff Mayfield wrote of the chart in a front-page story that week ("A New Hot 100 Reflects Changes in Music Business").
Mayfield added, "While the goal was simple, the road that led to the methodology was long, often circuitous and frequently bumpy. The journey began three years ago, when the only immediate conclusion that became obvious is that there would never be a consensus among labels and distribution executives as to the perfect recipe for this landmark chart."
Ultimately, Mayfield explained, "months of thought, experimentation, test charts of various ingredients and countless hours of discussion" led to that issue's new-look Hot 100. Also put into effect that week, reflecting the shift to a more inclusive chart: an expanded Radio Songs panel. Previously the domain of mostly top 40 stations, along with adult pop and alternative, the chart grew to the all-genre-based ranking that it is today, mixing in country, R&B/hip-hop, Latin and more.
Instantly, the Hot 100 restored its status as an all-encompassing picture of the biggest weekly hits, even if some weren't available as commercial singles. That week in 1998, a staggering 60 songs made their first visits to the Hot 100 (although note that the "last week" column in the above image showed ranks from the prior week's unpublished test chart). Goo Goo Dolls' "Iris" spent its 18th and final frame at No. 1 on Radio Songs (still a record) but appeared on the Hot 100 for the first time, at its No. 9 peak. Other airplay-only hits including Shawn Mullins' "Lullaby" (No. 12, before peaking at No. 7), Eagle-Eye Cherry's "Save Tonight" (No. 14, ahead of a No. 5 high) and Alanis Morissette's "Thank U" (No. 17, its peak after it had already hit its airplay highpoint) were likewise granted Hot 100 access at last.
(Also new that frame, at No. 21: Aaliyah’s “Are You That Somebody?,” the top song of 1998, per Billboard’s critic’s picks list of the year’s top 98 titles.)
One of the most notable newcomers that week: Natalie Imbruglia's "Torn." The hit had topped Radio Songs for 11 weeks beginning in May 1998 but was not a commercial single. On Dec. 5, it ranked on the Hot 100 for the first time … at No 47. It rose to No. 42 the next week before departing, and, thus, stands as perhaps the best-known No. 42 hit in the Hot 100's history. (No offense, Bruce Springsteen's "Badlands," Hilary Duff's "So Yesterday" and Ed Sheeran's "Lego House," all of which also peaked at No. 42.)
'DESERVING' HOT 100 No. 1s THAT MONEY COULDN'T BUY
Going forward, more songs were still not released as commercial singles, but nevertheless became big airplay hits and, unlike before the Hot 100's rule change, showed on the chart, even if the lack of sales points on the survey hindered their chances of hitting No. 1. Among them, in 1999-2000: Backstreet Boys' "I Want It That Way," Smash Mouth's "All Star" and *NSYNC's "Bye Bye Bye," all of which topped Radio Songs but stopped at Nos. 6, 4 and 4, respectively, on the Hot 100.
Then again, from labels' points of view, sacrificing potential No. 1 Hot 100 hits by withholding physical singles was offset by a host of album success stories: Backstreet Boys' 1999 LP Millennium became the first to launch with over 1 million in weekly sales (1.1 million, according to Nielsen Music), while *NSYNC's No Strings Attached in 2000 soared in with 2.4 million, a one-week mark since bested only by Adele's 25 (3.38 million) in 2015.
Plus, 2000 brought the first Hot 100 No. 1 that reached the summit from airplay points alone: Aaliyah's "Try Again," that June 17. "Consumers who wish to purchase the No. 1 song in the U.S. have to buy the soundtrack album Romeo Must Die," Fred Bronson noted in that week's Chart Beat column. Wrote then-Hot 100 chart manager (and now vp of charts and data development) Silvio Pietroluongo, "In this heavily researched radio environment, a song such as 'Again' doesn't achieve its lofty place on a station's playlist without a demand from listeners to hear it. So, while it's not available at retail, there's no denying that the pervasiveness of 'Again' makes it a deserving No. 1 Hot 100 song."
Of course, not long after, the definition of a single would change once more, perhaps more so than ever before, as the early 2000s brought the advent of download sales, led by Apple's iTunes Store. With all tracks suddenly available for individual purchase, lines blurred even more greatly between album tracks and singles (although radio hits continued to receive labels' promotional pushes, as they still do).
On Feb. 12, 2005, the Hot 100 underwent another retail-based shift, incorporating digital song sales into its mix for the first time. Today, download sales have followed physical sales in decline and, as reflected by the bow of the Streaming Songs chart in 2013 as part of the Hot 100’s data feed, streaming followed as consumers' most immediate option to experience a song, and the most dominant metric for a majority of Hot 100 hits.
In that light, the then-new rules that Billboard implemented to the Hot 100 in December 1998 were significant, but the "changes in the music business" that Mayfield described weren't at all done. Soon, discussion of physical singles would give way to that of downloads, and, later, to streaming, reinforcing that change is the only constant when it comes to music and the charts. As soon as one chart change goes into effect, it's likely only a matter of time before platforms alter again and other modifications are on the way.