SIDE_DATA, what is it, do I need it, what do I do if I do?

[Falloutboy]

Tonight one of my DVDs when ripped showed SIDE_DATA both in the video and audio streams, I don't know exactly what this is, I have heard about streams dovi for Blu Rays:

Is the DVD equivalent to a dovi stream?
Do I need it?
Will my DVD look odd without this stream data?
Can I decode the streams with SIDE_DATA intact so that when I re encode it is included in the overall file instead of being "SIDE" data.

TL;DR - clue me in about SIDE_DATA.

Thanks.