"IT." That thing that makesa a pop-song more than just popular. That song that just has something as indescribable as "it." That makes you lose your voice from singing in the car. That you'll see a pack of girls dancing and singing to while stuck in a freeway traffic jam.

XM Satellite Radio is celebrating all the songs that have "it" starting on Friday, August 18th, with a special rolling countdown of every hit song, decade by decade, spanning multiple music channels.

From the 40s on 4, to the 50s on 5, 60s on 6, 70s on 7, 80s on 8 and... yep, the 90s on 9. Starting off with music from the Roarin' 20s, all the way until through end of the millenium, and finally concluded with a countdown of the hit songs from 2005.

IT: History of Pop on XM Satellite Radio will be a musical event you won't want to miss. Check here for the full schedule and details.