Sorting (asymptotic) complexity problem

Hi all,

I have some problems with "asymptotic notations". I have already learned the thery about that but there is still something unclear for me "in practice".

Let me show you some simple example:

Let's say we have the "__Selection__" sorting algorithm. The fact is it has the time complexity of "**O(n^2)** (squared)". **But what does it exactly mean?**

Does it mean that at worst case this algorithm makes *n^2* comparisons or *n^2* selections or *n^2* assignments or *n^2* "something else"?

In other words, how can I simply and logically find out the complexity of some algorithm?

Thanks.