Love is how you feel about someone.
What is love?
Baby don't hurt me, don't hurt me no more....
Okay, if you didn't get the song reference above then sorry about that. I just had to say that.
But if you are seriously asking on what love is, then according to Wikipedia, it is "a variety of different feelings, states, and attitudes that ranges from interpersonal affection to pleasure. It can refer to an emotion of a strong attraction and personal attachment." Usually you'll know it when you feel it because you'll feel good and you'll care for the people who you love.
There are many examples of love and how it's expressed. Love is dying for the one you love, always being there for that person no matter what happens; giving them your all. Love is unconditional.
Love can never be defined