YouTube is facing its first formidable competitor—and it’s coming from Instagram.

Yesterday Instagram released IGTV, a stand-alone app (and also a feature inside Instagram) that allows users to upload and watch videos that are as long as an hour in length.

Instagram’s parent company, Facebook, has been trying to develop video platforms for years. Why? Ads that run alongside videos cost more than ads that run next to photos. If IGTV works, it will boost the company’s revenue significantly.

Here’s what you need to know about IGTV.

What is IGTV?
Up until now, Instagram has allowed users to post short videos on their feeds and through Instagram Stories (which can then become more permanent “Highlights”). With IGTV, content creators can upload long-form videos. And, in the style of YouTube, the app spotlights popular clips from well-followed Instagram celebrities—efficiently guiding users who like browsing influencer-made content.

When I logged onto the stand-alone IGTV app this morning, it took me directly to a video of Glee star Darren Criss playing piano and singing “Gloria” in Italian. By clicking around, I moved on to artsy videos/ads from fashion brands including Dior and Prada and found myself falling down a proper IG hole by way of gorgeous outer space videos posted by National Geographic.

Yes, IGTV is essentially another YouTube. But it’s connected to (and embedded in) a wildly popular app, so it already has a built-in audience. Which is a huge plus for marketers.

What’s so great about it?
The coolest thing about IGTV, in my opinion, is that it showcases vertical videos—movies captured with your phone standing upright instead of on its side. Says Instagram, it’s “built for how you actually use your phone.” Amen.

And just as Instagram is fundamentally a better-looking, more cleanly designed Facebook, IGTV is a less cluttered and more attractive YouTube. But this isn’t an Instagram copy: IGTV has no feed, no still photos, and no Stories. You’re dumped directly into watching videos and can roam around from there.

Eva Chen, director of fashion partnerships at Instagram, posted one of the first videos on IGTV yesterday from a moving taxicab (she did a “What’s in Your Purse” video, where she chatted about items pulled from a see-through handbag).

By way of introduction, the fashion editor said, “We know 15 seconds is sometimes not enough to tell your whole story. Use IGTV as another way to stay in touch with your favorite blogger, Instagam-ers, and influencers…there’s great stuff out there.”

How can you use IGTV?
To use the app and feature, you’ll need to create a channel (not a profile) that will be matched with the profile you use on Instagram. Once you do that, you will automatically see content from people you follow on Instagram.

If you want to use IGTV from inside your Instagram app, look for a little button that pops up when people you follow have posted a new video.

To make your own video, tap your profile picture, then click the plus sign button to upload a video—which you don’t actually make on IGTV, but on your phone or through another video app.

As you’re likely gathering, all of this takes a little practice to master. But if IGTV turns out to be as popular as Instagram, you’ll be glad you were an early adopter.

Top: Instagram CEO Kevin Systrom announcing IGTV in San Francisco (courtesy of Instagram)