Envy: it's an unflattering, miserable emotion. And it's universal. All of us, at some time or another, will experience that feeling of wanting what someone else has, and resenting them for having it.
Of course, like all human emotions, envy has a purpose. It's a tool for social comparison, one that can alert us to imbalances in the social hierarchy. Sometimes, these feelings of envy can prompt us to improve our lives, says Harvard social psychologist Mina Cikara.
"If you have more than what I have, I may be inspired by what you have," she says.