While salary negotiations are a very uncomfortable task for most people, it is inevitable that all of us have to do it. So we either have to learn to become good at it, or fail and be doomed at a job that doesn't pay you what you are truly worth. 

That can in turn cause resentment to your employer and as a result diminish your performance, acting as a chain reaction until you eventually decide to quit and start the process all over again.

It's therefore important to not only know your worth, but know how to negotiate to get what you're worth.