What is your definition of happiness?

My writing ielts yesterday had a question, “what is your definition of happiness?”  I don’t even know. even I have never asked myself about this until now.
By chance, today while i was passing across a coffee shop I heard a an old song which I used to love a long time ago, I felt happy. Now I recall the feeling when from the first time I set foot in s Sydney, or when i was had just received my first week’s salary from my part-time job. i I was joyful all the way back home and treated myself to a favourite(american spells as favorite) food(but with my second week’s salary I didn’t have that feeling).
mMaybe with me happiness is every simply simple small moment which i can enjoy in my life.
However, happiness is hard to define exactly because it depends on the pont point of view and life style of each of us.