Emotional intelligence is one of the most important skills in modern workplaces. It first went mainstream in the mid-1990s, when Daniel Goleman’s book Emotional Intelligence became a bestseller. Goleman defines emotional intelligence, also known as EI or EQ, as “a person's ability to manage his feelings so that those feelings are expressed appropriately and effectively.” It is another kind of brain power, which, rather than helping solve puzzles, helps us regulate our emotions and understand others. Goleman claims that emotional intelligence is the largest single predictor of success in the workplace.