What Exactly is LOVE? What is EGO?

If we agree that LOVE is part of the human psyche and if we agree it is important for the development of any human being, how do we learn to LOVE?

Who teaches us the meaning of LOVE so that we know how to progress in learning?

And what is ego? We know of the word but do we really know its implications and whether it affects or not, our ability to truly LOVE?

How do we measure LOVE? Is it an inner feeling or an external response we get from others by which we measure?

Is love different by culture or is it a universal understanding? How does it affect us cross-culturally?