Love is an unconditional affection with no limits or conditions: completely loving someone. It's when you trust the other with your life and when you would do anything for each other. When you love someone you want nothing more than for them to be truly happy no matter what it takes because that's how much you care about them and because their needs come before your own. You hide nothing of yourself and can tell the other person anything because you know they accept you just the way you are.
This emotion, bring tears to our eyes when something happens to our family members, friends, even pets. When we feel love ripped from us, as in death or being rejected by another, we do things we wouldn't normally do, such as go on violent rampages, or mourn to the extent that our loved ones have to watch us constantly to make sure we don't try anything like suicide. Some can move on, always remembering the lost loved one after a while, but others cannot let go. These are the ones that need our love and support the most.
Love towards our friends, this is what helps us get along so well, and why we miss them when we don't see our friends for a long time. It's also why we hold certain friends over others no matter what happens. Sometimes, the bond between friends deepens to the point where a stronger bond of love is made, making them family.
Family bond's brought about the phrase, blood is thicker than water. We will do things for our brothers, sisters, mothers, fathers, and children before we would even consider doing them for anyone else. Many wars have been started because of this family level, brother avenging brother or father. This simple family bond can even extend to include our pets.
Summed up, love is feeling for another person so pure and sacred that nobody can define it to its true extent. It is what a person feels for another without any kind of physical or mental barrier between them. They live purely to be with the other to share experiences, pleasures, problems and pain.