This differs. But for me, it is something you feel for someone who you would give up anything for. Without them, the world is irreversibly incomplete and you are no longer satisfied with anything. You need them so much; life is better just because their heart is still beating. No one is better than them. They are the best for you and in your eyes they are perfect. Any moment not with them is just a waste of this infinite life in which you hope to spend all your days with them. When you feel deep down they are there. They help you through anything and everything, not caring if they get anything out of the efforts. When somethings up, they never settle for an "I'm okay." When you shout or lose your temper and hurt their feelings after a while they will forgive you (even when you still feel like a complete ****). This is because they love you. Love at times is not mutual. Nor is it perfect. But when anything is in doubt, just ask them. They will know. And be honest if they don't. No one is flawless, and we all have mistakes. But making mistakes for that one person is all worth it if it means seeing them smile. When you embrace your arms around their body life seems at its peak. Nothing is better at the time; No matter the time or place or whatever situation there may be. You feel fearless with them, and if they don't. It wouldn't matter too much. After all, it's love.