The best kind of happiness is kind that relieves a fear.

And I think it has something to do with nearly every happiness. Examples: love (eliminates the fear of being alone--living, dying, going through times of trouble, worry by oneself), sex, having money, completing projects/work, receiving a gift (someone likes you; you won't have to spend money on the item yourself; the item will help you in some way, etc.), and so on.