soreness of knees and ice vs hot bath

Hi all, I've gotten pretty sore knees probably because I'm not that athletic or flexible and I've been playing basketball everyday. I heard ice on the knees would help. Anything else?

My second question was just when do you wanna use ice vs using heat? Like, I always like using heat to relax but something like my knee soreness, they tell me to use ice instead. Could someone explain a bit?