Is it bad to hold in your farts?

I figure it is, but what can happen if you do it a lot? Farting is something that needs to happen. It's natural. but people are offended when you let them out, WHY???? It can't be good to continuously hold them in. Sometimes you have to hold them in in certain situations, but sometimes it's not that bad but you just don't want people to be like " Ugh who farted? That's gross!!!"