Editing Music radio (section)

===Top 40===
The original formulaic radio format was [[Top 40]] music, now known within the industry as [[contemporary hit radio]] or ''CHR''. In this radio format, disc-jockeys would select one of a set of the forty best-selling singles (usually in a rack) as rated by Billboard magazine or from the station's own chart of the local top selling songs.  In general, the more aggressive "Top 40" stations could sometimes be better described as "Top 20" stations.  They would aggressively skirt listener boredom to play only the most popular singles.

Top 40 radio would punctuate the music with jingles, promotions, gags, call-ins, and requests, brief news, time and weather announcements and most importantly, advertising.  The distinguishing mark of a traditional top-40 station was the use of a hyperexcited disc-jockey, and high tempo jingles. The format was invented in the US and today can be heard worldwide. Todd Storz and Gordon McLendon invented Top 40 radio.  Bill Drake and Rick Sklar have had a lasting modern influence.<ref>{{cite web|url=http://davemartin.blogspot.com/2004/09/it-requires-very-unusual-mind-to.html|title=N=1|first=David|last=Martin}}</ref>

Variants and hybrids include the freeform-like [[Jack FM]] (mentioned below under Freeform Rock) and the "Mix" formats mentioned below under Oldies. Top 40 music is heavily criticized by some music fans as being repetitive and of low quality, and is almost exclusively dominated by large media conglomerates such as [[iHeartMedia]] and [[CBS Corporation]]. Top 40 tends to be underrepresented on the Internet, being mostly the domain of commercial broadcasters such as [[Virgin Radio|Virgin Radio UK]].

Some of the most famous Top 40 stations {{Clarify|date=May 2010}} have been Musicradio 77 [[WABC (AM)|WABC]]/[[New York City]], Boss Radio 93 [[KHJ (AM)|KHJ]]/[[Los Angeles]], The Big 89 [[WLS (AM)|WLS]]/[[Chicago]], [[CHUM (AM)|1050 CHUM]]/[[Toronto]], Famous 56 [[WFIL]]/ [[Philadelphia]], and The Big 68 [[WRKO]]/[[Boston]]. Today, there are popular Top 40 stations such as [[WHTZ|WHTZ-Z100]]/[[New York City]], [[KIIS-FM|102.7 KIIS-FM]]/, and [[KNX-FM|KAMP-97.1 AMP Radio]]/ in [[Los Angeles]], and [[Jovem Pan]] in [[Brazil]]