What they are, and how they work.
Robert Emmons on how gratitude benefits us:
The social benefits are especially significant here because, after all, gratitude is a social emotion. I see it as a relationship-strengthening emotion because it requires us to see how we’ve been supported and affirmed by other people.
Indeed, this cuts to very heart of my definition of gratitude, which has two components. First, it’s an affirmation of goodness. We affirm that there are good things in the world, gifts and benefits we’ve received. This doesn’t mean that life is perfect; it doesn’t ignore complaints, burdens, and hassles. But when we look at life as a whole, gratitude encourages us to identify some amount of goodness in our life.
The second part of gratitude is figuring out where that goodness comes from. We recognize the sources of this goodness as being outside of ourselves. It didn’t stem from anything we necessarily did ourselves in which we might take pride. We can appreciate positive traits in ourselves, but I think true gratitude involves a humble dependence on others: We acknowledge that other people—or even higher powers, if you’re of a spiritual mindset—gave us many gifts, big and small, to help us achieve the goodness in our lives.
Don’t miss the list of benefits. The whole article is a good read.