"What exactly is the happiness?"
Is it just a state of mind, rather a temporal state of mind. Some humour, jokes or entertainment. Surf it on the Internet, it's written everywhere that it is within us itself. It is hidden in our own mind. But where exactly is this treasure box in our minds.
Examining the situation with the view of economics suggests that demand of happiness is extremely high but supply abysmally low. Everyone looks in need of it. Which implies that the one who can sell happiness can become the richest guy on this planet, perhaps without incurring any sort of expenditure. Be the richest guy by making people happy around you. You'll be the richest, in-fact the happiest, person. Happiness grows by sharing happiness. It's in "Be good , Do good"
Happiness is always in disguise. There is nothing like absolute happiness. It is in talking to your best buddies. Happiness is in being inane, being crazy, being yourself. It is in helping, in giving, in blessing and many more. Happiness is not spending the rest of life looking for it. It is in forgiving, it is in living; Living the life itself.
PS: Do read the comment mentioned below.