Introverts and extroverts describe people's attitudes about interaction.

The main difference between the two is that extroverts are energized by spending time with others, while introverts get drained. On the flip side, introverts need to recharge by spending time alone, while extroverts are drained by excessive alone time.

That's not to confuse introversion with shyness or extroversion with assertiveness - they're not the same thing at all. For instance, I'm a roaring introvert, but I'm not at all shy. I just need a lot of alone time, or time spent with one or two close friends - especially after, say, a party or something where I'm surrounded by people.

Of course, no one is solely one or the other; people just lean towards one side of the spectrum. If one of my descriptions fits you better than the other, then that's good enough. But if you're interested, the Myers-Briggs psychology test classifies personalities as either introverted or extroverted (in addition to a few other classifications), and the test is available free online. (Granted, I'm not sure that the free online tests are the same or as detailed as the actual psych test - people are supposed to be certified to administer it - but they're kind of fun to fill out anyway.) Here's a link to one, or you can Google it and see what comes up.

http://sminds.com/mbti/

Introvert and extrovert are psychological types. This concept was created by Carl Gustav Jung and is part of the Psychology of Personality. There are a lot of grossieres distinctions between these types.
An extrovert would have the following traits: sociability, activism, dominant, warmness, gregarity, positive emotions, intolerance to solitude.An extrovert has a higher sensory threshold than an introvert which means that he/she will (for example) listen to music louder than an introvert does.
Also, introverts are more sensible to negative feelings, they get more easily depressed. Being self-oriented, an introvert will perceive pain or feelings in a more complex manner. A test performed on babies revealed that the ones who cry more, become introverts ( they have a more developed sensitivity regarding sorrow or the absence of a loved person).
The fact is that Jung also described 4 essential ways through which humans experience the world : sensation, intuition, affect and rationality. One person can use all 4 but one of them will be dominant. By combining these 4 with the 2 personality types we have 8 types of personality as follows :
Introvert - reason = interior oriented, especially to an ideatic world.
Introvert - affect = Reserved but sympathetic, afectuos but nondemonstrative.
Introvert sensation = More interested in actually kinestezicaly sensing an event then interested in the actual event.
Introvert - intuition = More interested in the future then the present. Searching for the potential evolutions of an idea.
Extrovert - reason = logical person, not carying to much about a relationship, represses his/hers emotions.
Extrovert - affect = relies moreover on interpersonal relationships.
Extrovert - sensation = Aware of facts and details, good analytical capacity.
Extrovert - intuition = Adventurous, preoccupied in changing the possibilities of the external universe.

Introverts tend to be people who are shy and do not mingle in crowds. These are people who are quiet and do not talk often. They are calm and reserved. Extroverts are people who love to talk and interact with others. They are very social. Extroverts love to be out and about with others. They are usually very animated and talkative.

I tend to be both. Some days I am not very talkative and tend to keep to myself. I have other days where I want to interact with my friends a lot. I tend to be more of an extrovert these days than an introvert though since I want to become a teacher. It is important to be able to talk and be active in that field

People who are introverted tend to keep to themselves and prefer their own company. Socially they are more likely to hold their emotions in and refrain from sharing their opinions. Extroverts are the opposite. These social beings prefer to be around people and sometimes may over share information. If an extrovert has a problem or opinion it is likely that everyone they run across is going to hear it.

The introverts are shy and the extroverts gregarious. You may not be either one, you may be somewhere in the middle

Introversion and extroversion are two of many types of human personality.

Introverts and extroverts are individual that so-called possess these personality, respectively.

Introverts are usually used to describe people that enjoy spending time alone or with small group of people, more than being in a large social gathering. Their activities revolves around self-awareness and solitary.

Extroverts, on the other hand, prefers group-works, parties, and other activities that relates more social interaction.

While everyone is not so different to an extent, you can take a "Myers-Briggs Type Indicator" to find out which type you're more of.

Extroverts generally enjoy being out with other people, they like to socialize and often have many friends. Introverts tend to be more private and quiet. Often they are thought to by shy.
How do you know? Do you normally find yourself at the center of everyone's attention? if so you're an extrovert. If you're more of a wall flower then you might be an introvert.