Not long ago, the introvert was commonly viewed as the sad, lesser flipside of the extrovert. We now know better, recognizing introverts as having unique gifts that enrich not only themselves but society as well. Still, confusion reigns as to what it means to be an introvert, especially because the term is so often used as a synonym for shy, or to describe someone dealing with social anxiety disorder. It doesn\u2019t help that even the experts sometimes disagree on where the lines should be drawn. In general, however, the three terms are recognized as distinct categories that only sometimes intersect. Here\u2019s how it breaks down: Introversion The psychologist Carl Jung first introduced the terms introvert and extrovert in 1921 as a way to differentiate between those who feel more connected to their inward thoughts and feelings and those whose focus is more on the external world. Other researchers have added and subtracted to Jung\u2019s work over the years and there remains no single definition, but most agree on the basics. The introvert: \tEnjoys time alone. Indeed, that is how they recharge. \tNeeds less stimulation than the extrovert. An evening with a good friend of two is generally much more desirable than a large party, for example. \tTends to have powerful skills of concentration and to prefer immersing themselves in one task at a time. \tQuickly wearies of small talk but often enjoys digging deep into a topic. \tThinks before they speak and is often characterized as a good listener. \tMay be socially adept but quickly tires of parties or group gatherings where they must be \u201con\u201d for long stretches. Their social energy is limited, and they guard their supply. How personality comes into being is not perfectly understood, but both environment and genetics are believed to play a role, with recent research revealing that the brains of introverts and extroverts respond to experiences differently. It\u2019s important to note that no one is only an introvert or an extrovert; each of us contains at least a little of the other. There are also ambiverts, those who are neither predominately introverted nor extroverted. Introverts are often content to be behind the scenes, but they are also found in even the most high-profile positions \u2013 among business and political leaders, writers, artists, entertainers, even public speakers, using their prodigious powers of concentration and introspection. They may adopt a more extroverted demeanor when the occasion calls for it and then recharge in solitude. Shyness\u00a0 People who are introverts often describe themselves (or are described) as shy, but shyness and introversion are not the same thing. Shyness has, at its heart, a fear of negative judgment by others. Think of the difference this way: If asked to a party, an introvert might think about whether they wanted to expend their precious supply of social energy. A shy person, however, might think about how others at the party would perceive them. As author Susan Cain explained in \u201cQuiet,\u201d her landmark book on introverts: \u201cShyness is the fear of social disapproval or humiliation, while introversion is a preference for environments that are not overstimulating.\u201d One stays home from the party from preference, in other words, and the other from fear. Shy and introvert do sometimes overlap, of course, especially if the introvert has been made to feel as though their low-key personality is somehow less desirable than an extroverted one. There are shy extroverts too \u2013 those who enjoy the stimulation of the crowd while simultaneously dreading being at the center of its attention. Unlike introversion, shyness is better understood as a response, rather than a state of being. It\u2019s the social discomfort we feel whenever we worry about measuring up or appearing out of place or awkward. And that applies to all of us; everyone experiences shyness from time to time. Some embrace their shyness, seeing it as a personality characteristic that makes them who they are and that needs no overcoming. But if your shyness is preventing you from living the life you desire, however, reach out for help from your doctor or a psychologist. Social Anxiety Disorder Social anxiety disorder can seem like shyness on steroids, but the two are separate conditions despite occasional overlap, a 2011 study confirmed. Social anxiety disorder, also called social phobia, is an overwhelming fear of being humiliated in front of others. For some, this extreme self-consciousness means even simple actions such as eating in public or talking to a store clerk can be overwhelming. Blushing, trembling, sweating and nausea are common, and only add to the distress level. Social events are often agonized about weeks before they arrive. Friends, not surprisingly, can be hard to find and keep. An estimated 15 millions Americans are thought to have social anxiety disorder, according to the National Institute of Mental Health. Some are affected only in certain social situations while others find all social encounters unbearable. As to its cause, no one yet knows, but social anxiety disorder can run in families, suggesting a genetic link. Getting help is essential, not only because social anxiety disorder can make life difficult but because it is often associated with other anxiety issues or depression and can sometimes lead to substance abuse by those attempting to medicate away the negative feelings. Psychotherapy, particularly cognitive behavioral therapy, has been shown to be effective in treating social anxiety disorder. Anti-anxiety medications and antidepressants can also help in some cases.