Reddit’s that website you’ve heard of but maybe don’t quite understand. Is it a social network? A message board? Its spare design and free-for-all culture can be intimidating, but don’t underestimate its users’ collective power — for good and, sometimes, not-so-good. The site is one of the Internet’s most visited destinations, with billions of page views each month. One of Reddit’s co-founders, Alexis Ohanian, will be in town Thursday, talking at the Walker Art Center about his book, “Without Their Permission.” Ohanian shares his thoughts on Reddit and ways the Internet is “making the world suck less.”

What’s Reddit?

Reddit.com is a message board and online community. Users post links and photos, people comment, discussion (sometimes wild) ensues. Popular posts rise to the home­page, which calls itself “the front page of the Internet.”

Subreddits

Within Reddit, there are thousands of subreddits, a k a categories, set up and moderated by users. A category for cute pictures? That’s marked r/aww. Or maybe you’re into pens? Try r/fountainpens.

If you go What: Alexis Ohanian, co-founder of Reddit, talks about “Creative Entrepreneurship: Making the World Suck Less.” When: 7 p.m. Thu. Where: Walker Art Center, 1750 Hennepin Av. S., Mpls. Tickets: $15 general, $10 Walker members. Info: www.walkerart.org.

Upvoting, downvoting

Reddit’s big on democracy, allowing users to collectively elevate or bury posts. Like what you see? Click the “up” arrow. Annoyed or disgusted? Click the “down” arrow.

Founded, then sold

Ohanian and friend Steve Huffman founded Reddit in Massachusetts in 2005, then sold to Condé Nast in 2006. It’s now a subsidiary of Advance Publications, Condé Nast’s parent company.

Redditors

That’s what Reddit users call themselves. Reddit got its name because the founders envisioned people saying they’d “read it” on Reddit.

Anonymous

At a time when social networks like Facebook push real names and authenticity, Reddit is still all about anonymity. You don’t even need an e-mail address to be a member.

Boys’ Club

Six percent of Internet users visit Reddit, according to the Pew Research Center, which also notes men are twice as likely as women to use the site.

A quiet crowd

Reddit drew more than 90 million unique visitors in November, but just 2 million were logged-in Reddit account holders. Lots of lurking going on.

Karma

Those numbers posted next to your username are a measure of Reddit community cred. Post things people like and you’ll get “link karma.” Adding valuable comments earns you “comment karma.”

Acronyms Rule

Reddit is full of these. Some, like NSFW (not safe for work) are key to avoiding photos you don’t want to see. Others, like OP (original poster) are useful for following a discussion. A few more: CMV = change my view; TIL = today I learned; ELI5 = explain it like I’m 5 years old; and tl;dr = too long; didn’t read. Reddit offers guidance through the alphabet soup on its FAQ page.

IAmA...AMA

This very popular acronym attraction on Reddit stands for “I am a ... Ask me anything.” This is where people, sometimes anonymous regular folk with interesting jobs, sometimes celebs, field all kinds of questions from users.

Celebrity appearances

Reddit is becoming a must-stop for pop stars, authors, actors and politicians who want to show they’re tech savvy and connect with the people. President Obama, Arnold Schwarzenegger, Molly Ringwald and Keanu Reeves have all done AMAs.

Don’t be phony

Redditors are relentless in their demand for candor. Ask Woody Harrelson, who got virtually shouted down during an AMA when he tried to promote a movie rather than answer general questions.

Memes rise

That goofy meme you saw bouncing around social media? It likely started or gained momentum on Reddit, land of oddball humor and subreddits devoted to advice animals.

Animal mania

Reddit loves photos — especially those of cute animals. There are subreddits dedicated to cats, dogs, hedgehogs, red pandas, even sloths.

Big ideals

The lofty ideals of free speech and an open Internet reign. When Redditors felt threatened by federal legislation, they led a temporary Internet blackout in protest.

Fundraising powerhouse

When Redditors throw their support behind a cause, the money flows. A Minneapolis nonprofit raised more than $80,000 for a Kenyan orphanage in 2012 by posting a plea on Reddit.

Generosity abounds

There are entire subreddits devoted to being nice. For instance: r/Random_Acts_Of_Pizza, on which those in need ask for pizza and other redditors deliver. Also, worldwide gift exchange r/SecretSanta — even Bill Gates participated this year.

The Seedy underbelly

But the masses are sometimes a disgusting, misogynistic hive mind. There’s nudity, profanity and lots of comments that would make your mom blush.

Boston bombing

Redditors tried to help track down the bombers. They incorrectly pointed to a missing man, and mainstream media picked it up. Not good. Apologies issued all around.

Minnesota subreddits

Reddit is a global thing, but there’s plenty of local (or locally relevant) chatter. There’s all-purpose discussion on r/TwinCities. Winter outdoors? Try r/IceFishing.