Songs have the ability to transport you back to an exact "moment". It can be a particular event, or even just a particular phase of your life and how you felt during that phase.
As for me, the only song(s) that does not signifies any particular "moment" of my life would be my collection of Hindi songs - which is more regularly updated than the list of English songs in my iTunes. I think this is partly why I can listen to Hindi songs (or even let a Bollywood movie play) in the background while I'm studying or reading. My brain doesn't need to decipher the lyrics, my heart won't flashback random memories when it plays, I don't have to think about it and can maintain my focus.
But for English songs...
There's a song that would bring me back to an exact moment while I was driving in my car with my girlfriends, there's a song that can also bring me to a different moment in my car where I just drove aimlessly for about 30 minutes just because I wanted to be alone and let my mind be calm.. There's a song that can bring me back to that moment in the parking lot where a funny conversation happened relating to the lyrics of the song.. There are just many moments related to some songs for me and sometimes it's the reason why I don't listen to the songs anymore.
As for now, these are the two songs that would sum up my current "moment":