The "Billboard" Hot 100 is the music industry standard record chart in the United States for singles, published weekly by "Billboard" magazine. Chart rankings are based on sales (physical and digital), radio play, and online streaming. 

The weekly sales period was originally Monday to Sunday, when Nielsen started tracking sales in 1991, but was changed to Friday to Thursday in July 2015. Radio airplay, which, unlike sales figures and streaming data, is readily available on a real-time basis, and is tracked on a Monday to Sunday cycle (previously Wednesday to Tuesday). A new chart is compiled and officially released to the public by "Billboard" on Tuesdays. Example: 

The first number one song of the Hot 100 was "Poor Little Fool" by Ricky Nelson, on August 4, 1958. As of the issue for the week ending on October 7, 2017, the Hot 100 has had 1,067 different number one hits. The current number one song is "Bodak Yellow" by Cardi B. 

Prior to 1955, "Billboard" did not have a unified, all-encompassing popularity chart, instead measuring songs by individual metrics. At the start of the rock era in 1955, three such charts existed: 

Although officially all three charts had equal "weight" in terms of their importance, many chart historians refer to the "Best Sellers in Stores" chart when referencing a song's performance prior to the creation of the Hot 100; until the start of the rock era in 1955, radio was still in its Golden Age, characterized more by spoken-word programs than music radio, and physical record sales were still the dominant indicator of a recording's popularity. On the week ending November 12, 1955, "Billboard" published The Top 100 for the first time. "The Top 100" combined all aspects of a single's performance (sales, airplay and jukebox activity), based on a point system that typically gave sales (purchases) more weight than radio airplay. The "Best Sellers In Stores", "Most Played by Jockeys" and "Most Played in Jukeboxes" charts continued to be published concurrently with the new "Top 100" chart. QUESTIONS:

Q1:
1. What is the Billboard Hot 100 known for?
2. The Billboard Hot 100 is known as what?
3. 
Q2:
1. What is the name of the magazine that publishes the Billboard Hot 100?
2. The Billboard Hot 100 is published by what magazine?
3. 
Q3:
1. What is the Billboard Hot 100 chart ranking based on other than radio play and online streaming?
2. The Billboard Hot 100 chart ranking is based on what other than radio play and online streaming?
3. 
Q4:
1. What is the Billboard Hot 100 chart ranking based on other than radio play and sales?
2. The Billboard Hot 100 chart ranking is based on what other than radio play and sales?
3. 
Q5:
1. What is the Billboard Hot 100 chart ranking based on other than sales and online streaming?
2. The Billboard Hot 100 chart ranking is based on what other than sales and online streaming?
3. 
Q6:
1. What started happening in 1991?
2. 1991 was the year when what started?
3. 
Q7:
1. 
2. 
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Q8:
1. What did Billboard not have prior to 1995?
2. Prior to 1995, what did Billboard not have?
3. 
Q9:
1. What was radio mainly characterized by prior to 1955?
2. Prior to 1995, what was radio mainly characterized by?
3. 
Q10:
1. The first top 100 list was published on what date?
2. The publishing of the first top 100 list happened on what date?
3. 
