frame rate question
I am somewhat familiar with 24p and 60i and all of that and I searched past posts and didn't really see any post that covers my question. Forgive me if I missed it. I know what 24p and 60i are generally used for, 24p for a "filmic" look or to transfer to film and 60i for intentional television broadcast use like on a reality show or something. If that is the case, then what is 30 for? For what type of use would we need the 30 frame rate option? Also, if I intend to shoot corporate video and other things as such intended to be put on dvd, what frame rate should I use?