The song "Grease," sung by Frankie Valli in the 1978 movie, was written by Barry Gibb of The Bee Gees.

Prince Markie Dee of the comic rap trio The Fat Boys co-wrote the Mary J. Blige hit "Real Love."

If you have a whole day to kill, you can check out the full version of Pharrell Williams' "Happy" music video, the world's first 24-hour music video.

"Stop Your Sobbing" was first recorded by The Kinks in 1964. It became the Pretenders first single 15 years later, leading to a relationship between Ray Davies and Chrissie Hynde.

Donna Summer's "Bad Girls" is so catchy, it's easy to forget that it's about prostitutes. The song was deemed kid-friendly enough for the 2000 movie Rugrats In Paris.

Neil Young rarely allows his songs to be sampled, but he let the Canadian group Redlight King use "Old Man" in their 2011 song, also called "Old Man."
The Def Leppard frontman talks about their "lamentable" hit he never thought of as a single, and why he's juiced by his Mott The Hoople cover band.
The Third Day frontman talks about some of the classic songs he wrote with the band, and what changed for his solo country album.
In her days with The Runaways, Joan Jett saw The Arrows perform "I Love Rock And Roll," which Alan Merrill co-wrote - that story and much more from this glam rock pioneer.
Armed with a childhood spent devouring books, Mike Scott's heart was stolen by the punk rock scene of 1977. Not surprisingly, he would go on to become the most literate of rockers.
Guitarist Tony Iommi on the "Iron Man" riff, the definitive Black Sabbath song, and how Ozzy and Dio compared as songwriters.