Just 24 hours after Jack Dorsey officially took over as the new CEO, Twitter is finally rolling out Project Lightning, the multimedia update it has aggressively pitched for months, to resuscitate growth and get Twitter back on track with Wall Street.

In many ways, Lightning is Twitter’s most important product update ever. The new product, which Twitter is now calling Moments, is the kind of product that will shape how Dorsey is remembered in his third stint at the company he helped create.

A Moment is a group of tweets stitched together around a specific topic, such as the Super Bowl or a breaking news event. These Moments are curated by Twitter, or Twitter partners like BuzzFeed and the New York Times, and primarily exist within a new tab inside the Twitter app, although they can be shared as links within tweets as well. Moments tend to be multimedia-heavy, with lots of photo and video tweets included, although that isn’t necessarily a requirement.

Here’s an example of what a Moment looks like:

Unlike your Twitter timeline, in which tweets are typically read in reverse chronological order, Moments are constructed in the same way you’d read a book — with a beginning, middle and end. If you’re familiar with Snapchat’s Live Stories feature, which have become very popular with its users, you’ll notice some striking similarities. (Very striking.)

The purpose of the product is twofold. For starters, it’s a way for Twitter to play to its strengths by creating more content and engagement around live events, an area where Twitter truly does dominate other social platforms, including Facebook. When you follow a Moment, Twitter will temporarily insert tweets about that topic into your feed from people you don’t actually follow; as soon as the event is over, you’ll stop seeing tweets from those people. There’s no easy way to follow a bunch of people talking about a breaking news event, for example, so Twitter is trying to do that for you.

Twitter is also looking for ways to entice new users, and believes Moments may serve as the bait. Twitter can be underwhelming when you first sign up, admits Madhu Muthukumar, product manager for Moments. But if you can immediately follow a Moment — and all the important people contributing to that event — it’s easier to find interesting people and feel like you’re part of the conversation right away, he added.

“If it’s your first session [on Twitter] and you have no followings and no followers, boy, Twitter can be tough,” said Muthukumar. “This is meant to give you a bridge.”

Moments will also be added to Twitter’s logged-out homepage, which means they’ll be visible on Twitter.com to people without an account.

Twitter has never spent this much energy pushing a product launch before. On the company’s investor call Monday morning to announce Jack Dorsey as permanent CEO, Lightning was mentioned seven times. Twitter rolled out its entire exec team for a profile of the product back in June, almost four months before it was ready to launch.

Dorsey said on the company’s Q2 earnings call that previous product launches had failed to deliver the kind of results Twitter needed. It can’t afford to add Moments to that list, not after all the hype it created. On Thursday, Dorsey and Twitter’s top execs will show off the update to a group of advertisers in New York. Twitter is even planning a massive advertising campaign to get the word out to the general public.

“I’d be lying if I told you we didn’t realize this is a big launch — we realize that,” said Muthukumar. “We’re proud of what we’ve built. We’ve done a lot of work, but we also know it’s still the beginning, so in that way there’s not much pressure. If this comes out and it lights the world on fire — great. If this comes out and it’s not [lighting] the world on fire — that’s fine, we’ll iterate.”

Twitter won’t sell ads within Moments at launch, but Muthukumar says the company will eventually. Twitter won’t be pushing moments into people’s timelines, either; the company often suggests a tweet or a user to follow, but won’t do that with Moments, a spokesperson confirmed.

Update: Twitter already has a plan to monetize Moments. It will give brands their own Moments called promoted Moments which will exist for 24 hours at a time within the new tab, according to AdAge.

Only those in the United States will have the new Moments tab as part of an app update Tuesday, but because Moments are shared like all other tweets, they’ll be visible to Twitter users all over the world if those users come across a Moments link. The new tab is launching for iPhone, Android and the Web.