A typical Twitter feed is a stream of letters and words. There is photo-sharing, and plenty of it, but Twitter isn't meant for album-making (that's a job for Facebook, Flickr, Imgur, etc.); it's meant for real-time, text-based, 140-character updates.

And yet, every now and then, tweets like this one pop up:

Welcome to the world of Twitter art, a whimsical, boundless space dominated by image-generator bots and ASCII character codes and hand-drawn cartoons. Twitter art appears unexpectedly in streams. Twitter art is experimental. Twitter art even interacts with other Twitter art.

But Twitter art is also hard. Its creators face a tricky challenge: They work on a site designed primarily for posting limited text, so users rarely stop and stare at tweets the way they might pause to appreciate other visual art forms. "Twitter is not the best platform for sharing art because of its presentation," G.P. Lackey, an artist and one of the creators behind the bot @GenerateACat, says. "It's difficult because it has a constantly changing current."

Lackey and his fellow @GenerateACat creator Bronson Zgeb use the simplest method—uploading images through a bot—to get around Twitter's 140-character parameters. They treat the account like an online gallery-slash-laboratory that updates whenever a batch of new images are available. And there are hundreds of images they can feed into the account at a time. Each "cat" is created based on a combination of randomized characteristics, including color, shape, expression, and even whisker length. Add a randomly generated phrase to include with the cat, and voilà, a cat, generated:

The bots-and-online-gallery method is a popular approach. There are bots similar to @GenerateACat that make variations of one image (@GenerateAFace makes faces, @OmgGeospheres makes 3-D-looking faces), bots that create wholly random images (@GreatArtBot makes pixelated art), and bots that tweet archival content (@BookImages grabs historical images from books in the Internet Archive).

And then there are Twitter art bots that are interactive, that try to make their feeds more than just galleries. Lackey recommends @badpng bot, which re-encodes images into cacophonous line art, as well as @LowpolyBot, which regurgitates polygon versions of the pictures it receives, like this one (which also happens to be a response to another art bot, @A_Quilt_Bot):

But Twitter art isn't just about bots generating images and tweeting at each other (which, incidentally, another bot, @imgconvos, tracks and transforms into animations, because why not?). It's also for the artists who create ASCII or Unicode characters-based art without uploading images, willingly constraining themselves to Twitter's limits.

One of these artists, Matthew Haggett, created @tw1tt3rart in 2009 to join the few other artists who were making ASCII art on the site. Twitter's constraints didn't scare him off. "The limitation of 140 characters made it interesting," Haggett tells me. "There was definitely an element of puzzle-solving."

Over time, Haggett accumulated nearly 85,000 followers, and Twitter itself began to change. He notes how, when he started, he couldn't do line returns in tweets, so the art wouldn't "stack," and his illustrations would tend to look differently on mobile devices. Now, Haggett says, "Twitter has shifted away from text-only and towards multimedia with in-stream photos, videos, and the like. That opens the door to a lot of artists, and expands the ways for artists to share their content."

Those artists include Jonny Fox, creator of @ArtOnALine and its companion account, @C0NSTELLATl0NS, two popular ASCII-based Twitter art accounts, with about 40,000 and 3,500 followers, respectively.

Both manage to, despite the tougher challenge of correctly spacing the characters and fitting them into a tweet, transform the idea of a "tweet" and break up the flow of text in the news feeds of followers. Tweets can take many forms, from ones that display a few strategically placed words to ones that use other characters to make words themselves—creations that follow the basic tenets of ASCII art. Here, one @ArtOnALine creation uses emojis and forces the tweet to stretch down the length of the screen:

And here, a constellation:

While Fox drafts his tweets in his phone's Notes app, other Twitter art creators use bots to produce similar Twitter art. Katie Rose Pipkin, for example, uses bots like @100YearsRising (which illustrates sea level changes), @Tiny_Star_Field (which imagines clusters of stars), and @Unicode_Birds (which generates migratory flight patterns) to generate ASCII art.

Bot or not, a Twitter art account attempts to change the text-based site into something more—a gallery, an experiment, an experience. As Fox put it to The Airship:

I think there's definitely a deeper reason for Twitter art than just for fun... I think if I can make one person smile or provide them with a little bit of something different than all the celebrity nonsense and gossip and garbage on most people's Twitter feeds, then that makes it all worthwhile. It's good to see art.

That's the same idea behind Lackey's work—"The really basic goal that I want to achieve is to surprise you a bit," he tells me—as well as the one behind the most traditional Twitter art of them all: the art on @DrawnYourTweet. The cartoonist behind the account, Scott Weston, randomly chooses a follower and illustrates by hand a tweet he sees on their feed.

"My drawings are way of saying 'thank you,'" he explains in an email. "They're unashamedly whimsical and literal interpretations of other people's tweets."

Weston ends every tweet with a friendly "Enjoy," a word that could serve as the motto for all Twitter art. Because between the random bot-generated images and the carefully crafted ASCII art, these accounts do little other than please their followers and the people who stumble upon them, by tweeting light, often spontaneous content. They're just accounts that make art on Twitter, where a never-ending stream of text is—every so often, if you're lucky—punctuated by something else. Enjoy.