Tweets are short at 140 characters, but a Twitter avatar must visually represent a user in just 2304 pixels. Choosing the right avatar can affect the way people see you online.

Here are some of the most popular avatar types and what they say about the user:

Standard head shot: Head and shoulders, framed squarely, professional in appearance, though perhaps a little formal. You’ve established a good balance between being serious and frivolous. You’re “normal,” whatever that means. You’re in demand as a friend and as an employee and you’ve never been thrown out of anywhere. You’re taken seriously. You don’t have a hidden agenda and you’re not trying to be ironic. You probably listen to the Eagles.

Jaunty angle: Variation on the head shot with the torso and/or head at something near 45 degrees, bisecting the picture. You don’t follow the crowd. When others zig, you zag. There’s plenty of irony in your repertoire. You wink at people, and sometimes point at the same time. If you’re old enough, you’re upset that Zima is no longer sold.

Political dissident: Generally based on the previous avatar types, but modified to show support for a person, political cause, etc. Currently, the most popular of these is the green avatar to show support for free elections in Iran. Other variations demonstrate support for political candidates. If you’re a liberal, you have a green avatar and tweet from TweetDeck on your iPhone while driving your Prius. If you’re a conservative, you’ve probably changed your avatar to show your affiliation with TCOT (Top Conservatives on Twitter), even though you find grassroots political activism a little confusing.

Logo: A little impersonal but also a nice way to show affiliation with a brand. You represent the company 24/7, even when you’re blipping Lil Wayne at two in the morning or calling someone a social media douchebag. It’s all about the authenticity, baby.

Animal lover: Usually a picture of a cat or dog, but squirrels also seem to be popular. You’re all over the lolcats thing, and not afraid to tweet, “My cat just crawled across my keyboard. LOL!”

Life of the party: A person standing on their head, wearing a goofy hat, making a face or otherwise hamming it up. I really have to give these people credit. This is a breakout thing to do. What is it the young people say? You go!

Celebrity stalker: A photo of a well known figure, whether used deceptively, in parody, or merely to show one’s admiration for an actor, singer, politician, etc. It’s like Halloween 365 days a year. You’re Barrack Obama, Britney Spears or Rick Astley. (Rick Astley? People do crazy things.) I guess it’s all in good fun, but would you want someone using your picture and claiming they were you? It’s kind of creepy.

Brown box special: The tacky default Twitter avatar, indicating a new user, or a spammer, or both, or someone who is too private to post an avatar, or maybe too lazy. You have some deep issues, either manifested in sociopathic dishonesty or a paralytic unwillingness to commit.

Good ol’ days: Featuring the owner’s high school yearbook picture, baby picture or other reminder of a bygone era. You believe in good old fashioned values, like those espoused on Scooby Doo or Baywatch. You’re pissed at what’s going on this country and wish things were they way they were when you were a kid. (I’m with you on that.)

Cartoon: There are many variations on this one. Sometimes it’s an actual South Park character, other times it bears some resemblance to the user but is stylized to look like a South Park character. Anime/manga characters are popular too. This avatar identifies someone who is both a fan of Twitter and cartoons or comic books, which is a double threat if you get my drift.

I know there are more avatar types, like the family picture, or the beach at sunset, but how many people and their avatars can I offend in one post? If you have any favorites, please add them below with a comment. And go ahead and critique my avatar. (I can take it.)