Short answers, pulled from the story.
"Poor Little Fool" by Ricky Nelson was the first number-one song on the Billboard Hot 100, on the 4th of August 1958. That date also marked the chart's debut as Billboard's single all-genre singles ranking.
Journalists Tom Noonan, Paul Ackerman, and Seymour Stein created the Billboard Hot 100. Stein later said he did not recall who chose the name.
The Billboard Hot 100 ranks songs using a combination of radio airplay audience impressions, digital and physical sales, and streaming activity. Airplay is measured by Nielsen BDS across approximately 1,000 stations; sales and streaming are tracked by Nielsen SoundScan. The tracking week runs Friday through Thursday.
Streaming data entered the Hot 100 formula in the issue dated the 11th of August 2007. AOL Music and Yahoo! Music were the first services to supply weekly statistics. YouTube views were added to the formula in February 2013, and "Harlem Shake" was the first song to reach number one under those expanded rules.
Before the 5th of December 1998, a song had to be commercially available as a single to qualify for the Hot 100. Major labels stopped releasing singles in the 1990s to protect album sales, so airplay-only songs were ineligible. No Doubt's "Don't Speak" led the airplay chart for 16 weeks and the Goo Goo Dolls' "Iris" for 18 weeks, neither of them appearing on the main chart during that period.
Teddy Swims' "Lose Control" holds the record for the longest Hot 100 chart run, leaving the chart on the 25th of October 2025 after 112 weeks. That departure coincided with Billboard's major overhaul of its recurrent rules, enacted in response to streaming driving longer and longer chart stays.
Five artists placed a song in the Hot 100's top 40 in each of the four decades from the 1980s through the 2010s: Michael Jackson, Madonna, "Weird Al" Yankovic, U2, and Kenny G. Mariah Carey is separately recognized as the first artist to reach number one in four different decades.