What Exactly is True Altruism?

I often wonder what is true altruism? First, let's make an attempt to answer the following: Is true altruism the act of doing something or the result? I would think true altruism is the end result. If you are doing something other than the end result then you would be fulfilling your own desire or purpose. Right? For example, you may be compelled--to giving because of the emotional attachment or tension. Consequently, this begs the question of whether every decision is based upon personal merit, in the first place?