Love is a general term used to describe an attraction, enjoyment, or other positive interaction either between two people, or of one person towards another person, object, or idea. Love can also be considered to be any strong emotion which causes people to do things that they know to be dangerous or immoral. Thus, love is often expressed in patriotism, heroism, and murder. However, it is not uncommon to heard the term being applied in less emotional contexts, such as "I love chocolate".
Love can be more easily understood when considered as several different forms. Ancient Greek had three separate words for love: "storge", "eros", and "philia". The first, storge, refers to the type of love that a family member feels or displays towards another family member: devotion and union. Storge is the motivation for the aforementioned patriotism. Eros refers to a sexual type of love, that felt between a passionate couple. This is the root of the modern English word "erotic". Lastly, philia refers to the emotional love of an object or person, but with no deep emotional ties. This is the least strong form of the term, and the basis for friendship and affection.
The feeling of love can be attributed to certain chemicals present in mammals' brains at the time when love is felt, notably testosterone, oestrogen, and norepinephrine. Cultures which do not arrange marriages tend to believe that love is a random or uncontrollable emotion, and usually encourage couples to wait until love is felt before committing to marriage. In contrast, cultures in which arranged marriages are commonplace tend to believe that love can be manufactured within a marriage, and is therefore not a necessary prerequisite to marriage. Additionally, in several games, notably tennis and bridge, the term "love" is used as an indication of zero score. Other uses of the word are usually direct references to the emotion or passion associated with love.