Why is there intro/outro silence in songs?

So why was the Chillout Lounge forum closed and deleted? This type of question is prime candidate for said forum. WTF?

Anyway, just a random question I was wondering and was hoping some of you had an answer to why a lot of songs on CDs or whatever have moments of silence before and after the song, maybe a couple seconds, whatever. I know that sometimes songs were meant to be recorded one right after the other and it just sounds better with the fade out and fade in (for example, the Metallica S&M CDs).

It bugs me, especially when I'm driving in my car and have a mix CD and it shuffles to the next song but doesn't play right away (actually it does play right away, but there are those seconds of silence before the track) or the previous song takes a while to end before going to the next song (because it has like 3 seconds after it fades out of pure silence), which is probably most noticeable in Winamp since there is no lag between playing songs.

Almost all the music I get now I edit so that almost all the silence is taken out from the beginning and ending of the songs. I've got some random .mp3 and convert it to .wav and plug it into Sonic Foundry and zoom in to where the first and end sounds are and delete the silence before and after them, then I just re-encode it back to .mp3 using Exact Audio Copy. I keep the original .iso and encodings in an archival folder just for fun.

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