I'm 20, born in 1988. This is my personal musical definition of my generation / what helped me become the person I am. I know it's supposed to be broken up into songs and such, but the list would just be too long, so I'm gonna rattle off some bands and why I feel they defined MY generation.
For the longest time I really didn't get into much music. I grew up with a lot of mellow Christian music like Michael W Smith. My brother and some friends were heavily into punk and ska. I got into it, probably a little out of peer pressure though I still like some of it today. Back then it definitely shaped my life a bit as like I said there was some peer pressure there. Nothing negative, probably alot positively as 90% of that music was all Christian based as well.
So, from my childhood to young teens:
Supertones, Insyderz, Five Iron Frenzy, MXPX, Michael W Smith, Newsboys. Nothing else really noteworthy.
As me and those friends started growing up, we mostly grew apart. Tastes changed, found new hobbies, stuff like that. We were becoming what we are now. Very different people, really.
So there was a time when I grew enough away from that crowd that I didn't really have a genre of music I totally liked. I had nothing to really attach my liking of X style of music to, and with no one to listen with or talk about the music with I sorta just grew away from it. I still liked it, but it just wasn't as fun as it was when we were all into it I guess.
A few years, maybe till I was... 15 or so, I liked 'funny' music like Weird Al, They Might Be Giants, but never really got heavily into it. I didn't really have any music to call 'home' I can't say that any music had really defined my life from the age of 15 to 18. My taste in music was going through a rebirth. The roots of my current musical tastes start with bands like (including but not limited to) Evanescence, Chevelle, Linkin' Park, and Switchfoot.
From that point till now my tastes in music encompass most forms of modern rock (alternative, goth, some forms of punk, etc) and some metal and hardcore screamy type stuff. The metal and screamy stuff has been becoming a bigger interest lately with the discovery of a few bands, namely August Burns Red, Demon Hunter, and All That Remains.
The bands that have made me reflect on my life and want to change things the most would have to be Flyleaf, RED, Five Iron Frenzy, Demon Hunter, and August Burns Red. To me these are the bands that define my personal life. These are all great bands with great messages. If you like dark and heavy rock then you'll love these bands, but look deeply into the music. With the dark, hard, and heavy hitting lyrics and music comes extremely positive messages delivering hope to those who have little. These bands are the bands that I think I will hold most dear to myself for the rest of my life. They are the bands that are helping to form me into the person I have always wanted to be. They've helped me see a lot that's wrong with the world and people as well as myself and my own life. It makes me want to be different and set apart from the crowd.
I find it interesting that the great majority of my favorite bands are Christian. I listen to all genres of music, but it always seems that after I start falling in love with a band I find out they're Christian. I guess it's just because I msot like unique bands with positive messages.
Why did I post all this?

I guess it's just more complicated for me when it comes to the music I like hehehehe.