Orgasms.. what do they feel like?

My last sexual partner and I definitely had some great sex. However I think that the only time I orgasmed was when he ate me out (for like half an hour, he was dedicated)...

Except now that I think back on it, I'm not really sure if I did orgasm.

My question: what does an orgasm feel like to you? I'm trying to expand my knowledge of what they feel like to different people so I can recognize when I have one next time I masturbate, have sex, etc...

Anything helps xx