The Star Trek franchise contains two primary "universes" that exist independently of each other. A Kelvin timeline consisting of three feature films and a Prime timeline that covers literally everything else. This year, 2233, is the point at which the universe splits into Kelvin and Prime. None of this is important at the moment, because we stick to the Prime timeline much later in that order, but remember that for later.

Remember, there is actually a third universe, the "Mirror" universe, which we'll be getting to know soon, but this is a completely different matter, and for simplicity, our visits are not separate from the Prime episodes.