Why do we say SORRY?

Why do we say sorry? Is it because we really admit our faults? Or is it because we don’t want to have prolonged talks and arguments?

I opted to several days of silence. Days of analyzing myself and the situation. I’m thinking if I’ve just been so emotional or I just had enough. I believe that some arguments can be put in place without having to talk about it. I mean it can be better without even dealing with it. It gets better on itself. But there comes a time when you feel that you’ve had enough. That it’s time that your feelings should be taken cared of more cautiously.