Hello to people who are reading this!

I have decided to write an entry for I have two things I do not understand.

Question #1: Why do we throw out the constants when we say the complexity of an algorithm? For example, instead of saying O(2n), we just say O(n). Why is this? I cannot understand.

Question #2: What does amortized mean? I've heard that many times and I don't know what it means. Can some of you tell me?

Thank you in advance for your answers!