What is squirting

Su

Okay so I know I should already know this but I don't. I just got married and I've orgasmed lots with him. But I'm seeing people on here talk about a sensation of feeling like you gotta pee when you are going to squirt? I've felt that often with him but it hasn't led to anything because I get nervous and think it's actually pee so I tense up. So what is squirting exactly and how do I go through with it?