Oh, for years I denied it. After all, I have good social skills. I am not morose or misanthropic. Usually. I am far from shy. I love long conversations that explore intimate thoughts or passionate interests. But at last I have self-identified and come out to my friends and colleagues. In doing so, I have found myself liberated from any number of damaging misconceptions and stereotypes. Now I am here to tell you what you need to know in order to respond sensitively and supportively to your own introverted family members, friends, and colleagues. Remember, someone you know, respect, and interact with every day is an introvert, and you are probably driving this person nuts. It pays to learn the warning signs.

What is introversion? In its modern sense, the concept goes back to the 1920s and the psychologist Carl Jung. Today it is a mainstay of personality tests, including the widely used Myers-Briggs Type Indicator. Introverts are not necessarily shy. Shy people are anxious or frightened or self-excoriating in social settings; introverts generally are not. Introverts are also not misanthropic, though some of us do go along with Sartre as far as to say "Hell is other people at breakfast." Rather, introverts are people who find other people tiring.

Extroverts are energized by people, and wilt or fade when alone. They often seem bored by themselves, in both senses of the expression. Leave an extrovert alone for two minutes and he will reach for his cell phone. In contrast, after an hour or two of being socially "on," we introverts need to turn off and recharge. My own formula is roughly two hours alone for every hour of socializing. This isn't antisocial. It isn't a sign of depression. It does not call for medication. For introverts, to be alone with our thoughts is as restorative as sleeping, as nourishing as eating. Our motto: "I'm okay, you're okay—in small doses."

How many people are introverts? I performed exhaustive research on this question, in the form of a quick Google search. The answer: About 25 percent. Or: Just under half. Or—my favorite—"a minority in the regular population but a majority in the gifted population."

Are introverts misunderstood? Wildly. That, it appears, is our lot in life. "It is very difficult for an extrovert to understand an introvert," write the education experts Jill D. Burruss and Lisa Kaenzig. (They are also the source of the quotation in the previous paragraph.) Extroverts are easy for introverts to understand, because extroverts spend so much of their time working out who they are in voluble, and frequently inescapable, interaction with other people. They are as inscrutable as puppy dogs. But the street does not run both ways. Extroverts have little or no grasp of introversion. They assume that company, especially their own, is always welcome. They cannot imagine why someone would need to be alone; indeed, they often take umbrage at the suggestion. As often as I have tried to explain the matter to extroverts, I have never sensed that any of them really understood. They listen for a moment and then go back to barking and yipping.