Phthonos

Envy (from Latin invidia) is an emotion which "occurs when a person lacks another's superior quality, achievement, or possession and either desires it or wishes that the other lacked it".

Bertrand Russell said that envy was one of the most potent causes of unhappiness. Not only is the envious person rendered unhappy by his or her envy, Russell explained, but that person also wishes to inflict misfortune on others. Although envy is generally seen as something negative, Russell also believed that envy was a driving force behind the movement towards democracy and must be endured to achieve a more just social system. However, psychologists have recently suggested that there may be two types of envy: malicious envy and benign envy—malicious envy being proposed as a sick force that ruins a person and his/her mind and causes the envious person to blindly want the "hero" to suffer; on the other hand, benign envy being proposed as a type of positive motivational force that causes the person to aspire to be as good as the "hero"—but only if benign envy is used in a right way. Envy and gloating have parallel structures as emotions.

One theory that helps explain envy and its effects on human behavior is the Socioevolutionary theory. Based upon (Charles) Darwin's (1859) theory of evolution through natural selection, socioevolutionary theory predicts that humans behave in ways that enhance individual survival and the reproduction of their genes. Thus, this theory provides a framework for understanding social behavior and experiences, such as the experience and expression of envy, as rooted in biological drives for survival and procreation. Recent studies have demonstrated that inciting envy actually changes cognitive function, boosting mental persistence and memory.

Schadenfreude means taking pleasure in the misfortune of others and can be understood as an outgrowth of envy in certain situations.

Often, envy involves a motive to "outdo or undo the rival's advantages". In part, this type of envy may be based on materialistic possessions rather than psychological states. Basically, people find themselves experiencing an overwhelming emotion due to someone else owning or possessing desirable items that they do not. For example, your next door neighbor just bought a brand new ocarina—a musical instrument you've been infatuated with for months now but can't afford. Feelings of envy in this situation would occur in the forms of emotional pain, a lack of self-worth, and a lowered self-esteem/well-being.

...
Wikipedia