Baby don't hurt me, don't hurt me, no more... (I'm sorry I couldn't pass up the opportunity)
As far as I understand it, it is a strong attachment and desire to care for another person in your life. It can vary in intensity and manifestation, but the main factors typically remain the same.
When you love someone, you think about them even when they're not with you, and you feel happy when they are with you. You want them to be happy and well-taken-care-of, and different people express that urge in different ways.
Love can be toxic if it's too one-sided or if two people have a very different definition of how to take care of one another.
The only love I've ever experienced as an aromantic person (i.e. a person with little to no romantic interest in others) has been familial and platonic, so if an alloromantic (a person who does develop romantic interest) person has a better definition, listen to them! But I hope this helps clear things up a bit!