Why is there a point system in Chess?

Why is there a point system in Chess? I've never figured this out. 

Do you mean points or ratings?

Points, like a pawn is worth one, bishop worth 5, etc. 

Ah, I thought you may have been referring to chess.com's points system.

It's to do with how valuable the pieces are. And bishops aren't worth 5; they're worth just over 3 I believe.

They are a general guide for beginners and intermediates to a lesser degree when they perform exchanges.

However, the TRUE value of any piece depends on the global position and its position in that position (wow, redundant). Sometimes, a knight may worth more than a bishop - even though they are equal according to the points system - and maybe even a rook in some positions!

So you know who has more points when the game is over.

But the person who checkmates wins, regardless of points. 

General guideline for beginners, so that they don't make bad trades for no reason. And that's about it.