>>10
It's called encapsulation dipshit. Say you have a Shape object and, like the noob you are, you make its position variable public and use it all over your code. Then a year later you decide to extend Shape into a Triangle, where position doesn't make sense unless you go do some lengthy calculations to find its centroid. Way to go, now you need to encapsulate your triangle's vertices and re-check them every time in case someone fucked with your public position.
Encapsulate it properly, and you can write the vertex deltas into the setPosition method you extend. No wasted calculation time.
gb2/encapsulation/