What are "[ ]" square brackets used for?

Hi Everyone,

I have kind of a silly question.
I am kinda new to as3 and I have seen

[]

the square brackets used when trying to access array index but I have also seen some people use it in other places. I was just wondering what its exact function was:puzzled:.

If anyone is kind enough to explain this or if possible give a simple example, I would be really grateful.