Well...
In school terms, a feeling of deep affection for someone or something.
In MY terms, love is thinking about someone constantly. They always seem to be on your mind. You want to see them and talk to them at all hours. You care for a person not matter what their flaws are.
The Greeks believed in four different types of love: family, friend, romantic, and God love. Family and God love are unconditional, romantic and friend were not. However, romantic could become family love.
The Greeks were smart about love.
Love is a tricky subject, with deep roots in philosophy. Technically any emotion is just electrical signals firing across neurons in your brain, but love makes us do things no other emotion can do. Every emotion seems to be linked to love. To love is to be human, and to be loved is a great feeling.
People who can't feel love? Psychopaths and sociopaths. Often times it was because they weren't loved as children, abused or ignored by those around them. This can lead to sociopathic or psychopathic tendencies.
Anyway, love is crazy and indescribable. Hope this helps.
-Dylan