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Credit Jerod Harris/WireImage

They should post a sign in Anaheim, Calif., this week warning adults: “Keep out! Screaming teens everywhere.”

On Thursday, more than 18,000 star-struck frenetic teenagers will descend on the Anaheim Convention Center for VidCon, a conference for online video makers, where they will spend three days running around like total and utter lunatics, all the while recording, editing and live-streaming on their mobile phones.

These teenagers will be on the hunt for celebrities with names like Smosh, Burnie Burns, TheThirdPew, Markiplier, Ksiolajidebt, Connor Franta, Flula Borg and Superwoman. To you and me, these monikers are completely unrecognizable. Yet to the kids in Anaheim, these people are more famous and important than any other mainstream A-list celebrity.

Feeling old and out of touch yet? I am. And don’t worry, even people on the same stratosphere as these kids don’t get half of what’s going on.

“I’ve been to almost every major conference or fan event related to fandom, and never have I seen such mayhem and screaming that I have seen at VidCon,” said Veronica Belmont, an online video personality and the host of “Dear Veronica,” a show on Engadget.com. “Hotel lobbies are filled with flocks of teens that are like a force of nature, chasing after video stars that I have never even heard of before.”

This is exactly why VidCon has become so important culturally. The conference was founded in 2010 by two brothers, Hank and John Green, of the VlogBrothers YouTube channel. They are, as the kids like to say, kind of a big deal; Hank interviewed President Obama recently on YouTube, and John is the author of “The Fault in Our Stars.” In its short history, VidCon has become the barometer for just how quickly and fervently online video has changed.

“The generation that used to wait outside 1515 Broadway for MTV’s ‘TRL Live’ to finish taping is now the same generation that will be waiting outside of the Hilton Anaheim for their YouTube stars to come out,” said Casey Neistat, who is officially introducing his new video app, Beme, at the conference.

When VidCon began, there were 1,400 people in attendance, and almost all the video creators shared their shows on YouTube. Back then, most of those clips were viewed on a laptop. Now, five years later, the number of attendees has grown by 1,200 percent, and while YouTube is still insanely popular for video stars, clips are now created and watched on apps like YouNow, Snapchat, Periscope, Vine, Meerkat and Keek, not to mention new video features from Twitter, Facebook and Instagram.

For some people, all of these new apps and celebrities you’ve never heard of can feel overwhelming. But Hank Green sees the chaos and mayhem as a perfect indicator of why you don’t need to be apprised of every little thing happening with online video.

“You have to think about this like each platform is its own genre,” Mr. Green said in a phone interview. He likened the scads of video apps to the vast offerings on Netflix: There are thousands of options, and not everything will appeal to everyone, so users should only care about what they like. “It’s O.K. to not know everything about everything in the world,” he said.

The same applies once you go into the rabbit hole of each platform, where new shows often find their audiences through the proliferation of obscure, app-specific hashtags. Take #sleepingsquad, currently trending on the live-streaming app YouNow, which shows teenagers who film themselves sleeping for hours while onlookers watch and comment in real time.

Snapchat has thousands of bizarre little video trends, like ugly face contests, but these never reverberate outside a group of friends because nothing is posted to the Web. Another phenomenon, #SHTuesdays (Sexy Hips Tuesdays), highlights self-posted wacky videos of people dancing. That “show” is popular mostly on Vine, an app that will be representing in force at VidCon and that continues to mint new stars.

To put its reach into perspective, consider that one of Vine’s biggest stars today, KingBach, has logged more than 4.5 billion views on the platform, where he plays a dramatic, almost cartoonlike caricature of himself. By comparison, Justin Bieber (who often appears in KingBach’s videos) has been watched only 800,000,000 times on Vine.

Jason Mante, the head of user experience at Vine, said that these new stars have huge followings and will be chased after at VidCon because they spend so much time engaging with their audiences in a way that traditional stars do not. “When they post a new Vine, it’s not just stuffing a story into six seconds, it’s the next chapter or the next sentence of the larger story that they are telling,” Mr. Mante said.

So if none of this makes any sense to you, don’t fret. We now live in a world where your phone has become your television, and your apps have become the TV channels. Big stars are no longer created on big screens, but rather on smaller ones. And it’s perfectly fine if you have no clue who they are.