What happens if te cannot pray at the prescribed time of the day?

As-salaam alaykum! First off, I want to preface this da saying that I'm not actually Muslim, but merely interested in it as it is a beautiful religion, and want to find out più about it. Obviously prayer (salat) is a very important part of day-to-day life and is an obligation for the faithful. But what happens if one cannot pray at the prescribed time, due to circumstances such as school exams, being on public transport, etc? Is there an alternative? Thanks in advance!