Do you know someone who needs hours alone every day? Who loves quiet conversations about feelings or ideas, and can give a dynamite presentation to a big audience, but seems awkward in groups and maladroit at small talk? Who has to be dragged to parties and then needs the rest of the day to recuperate? Who growls or scowls or grunts or winces when accosted with pleasantries by people who are just trying to be nice?

If so, do you tell this person he is "too serious," or ask if he is okay? Regard him as aloof, arrogant, rude? Redouble your efforts to draw him out?

If you answered yes to these questions, chances are that you have an introvert on your hands—and that you aren't caring for him properly. Science has learned a good deal in recent years about the habits and requirements of introverts. It has even learned, by means of brain scans, that introverts process information differently from other people (I am not making this up). If you are behind the curve on this important matter, be reassured that you are not alone. Introverts may be common, but they are also among the most misunderstood and aggrieved groups in America, possibly the world.

I know. My name is Jonathan, and I am an introvert.

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.

Are introverts oppressed? I would have to say so. For one thing, extroverts are overrepresented in politics, a profession in which only the garrulous are really comfortable. Look at George W. Bush. Look at Bill Clinton. They seem to come fully to life only around other people. To think of the few introverts who did rise to the top in politics—Calvin Coolidge, Richard Nixon—is merely to drive home the point. With the possible exception of Ronald Reagan, whose fabled aloofness and privateness were probably signs of a deep introverted streak (many actors, I've read, are introverts, and many introverts, when socializing, feel like actors), introverts are not considered "naturals" in politics.

Extroverts therefore dominate public life. This is a pity. If we introverts ran the world, it would no doubt be a calmer, saner, more peaceful sort of place. As Coolidge is supposed to have said, "Don't you know that four fifths of all our troubles in this life would disappear if we would just sit down and keep still?" (He is also supposed to have said, "If you don't say anything, you won't be called on to repeat it." The only thing a true introvert dislikes more than talking about himself is repeating himself.)

With their endless appetite for talk and attention, extroverts also dominate social life, so they tend to set expectations. In our extrovertist society, being outgoing is considered normal and therefore desirable, a mark of happiness, confidence, leadership. Extroverts are seen as bighearted, vibrant, warm, empathic. "People person" is a compliment. Introverts are described with words like "guarded," "loner," "reserved," "taciturn," "self-contained," "private"—narrow, ungenerous words, words that suggest emotional parsimony and smallness of personality. Female introverts, I suspect, must suffer especially. In certain circles, particularly in the Midwest, a man can still sometimes get away with being what they used to call a strong and silent type; introverted women, lacking that alternative, are even more likely than men to be perceived as timid, withdrawn, haughty.

Are introverts arrogant? Hardly. I suppose this common misconception has to do with our being more intelligent, more reflective, more independent, more level-headed, more refined, and more sensitive than extroverts. Also, it is probably due to our lack of small talk, a lack that extroverts often mistake for disdain. We tend to think before talking, whereas extroverts tend to think by talking, which is why their meetings never last less than six hours. "Introverts," writes a perceptive fellow named Thomas P. Crouser, in an online review of a recent book called Why Should Extroverts Make All the Money? (I'm not making that up, either), "are driven to distraction by the semi-internal dialogue extroverts tend to conduct. Introverts don't outwardly complain, instead roll their eyes and silently curse the darkness." Just so.

The worst of it is that extroverts have no idea of the torment they put us through. Sometimes, as we gasp for air amid the fog of their 98-percent-content-free talk, we wonder if extroverts even bother to listen to themselves. Still, we endure stoically, because the etiquette books—written, no doubt, by extroverts—regard declining to banter as rude and gaps in conversation as awkward. We can only dream that someday, when our condition is more widely understood, when perhaps an Introverts' Rights movement has blossomed and borne fruit, it will not be impolite to say "I'm an introvert. You are a wonderful person and I like you. But now please shush."

How can I let the introvert in my life know that I support him and respect his choice? First, recognize that it's not a choice. It's not a lifestyle. It's an orientation.

Second, when you see an introvert lost in thought, don't say "What's the matter?" or "Are you all right?"

Third, don't say anything else, either.

Jonathan Rauch is a correspondent for The Atlantic and a senior writer for National Journal.