The "Since U Been Gone" singer, 42, returned to her daytime talk show on Tuesday after being out for almost two weeks. Guest hosts had stepped in for Clarkson during her unexplained absence.

Whatever it was, it might have left you wondering: what exactly do those late-night talk show hosts do, why are there so many of them, and what is the difference between them? Well, this handy ...

A new series from Radio Diaries remembers controversial broadcasters in American history, including Joe Pyne, who paved the way for in-your-face radio hosts like Rush Limbaugh.