Verizon is the latest pay-TV company to launch an internet TV service, following similar launches from Dish Network and Comcast. However unlike its rivals' versions, Verizon's Go90 is a mobile-first service aimed at millennials.

Verizon formally announced Go90 last week, but much of the initial coverage was light on details about what the service will entail. So here's an FAQ-style explainer describing the new app.

Why download the app if I'm already watching videos on TV, Netflix, YouTube, Facebook, Snapchat -- a lot of other places?

Part of that answer depends on how old you are. Verizon developed the app specifically for the demographic du jour: millennials. If you're in this age group, then Verizon thinks you'd find its mix of TV and digital content and on-demand and live programming right in line with your own viewing habits. Maybe you're just as interested in watching a live NFL game as a show from Vice. And maybe you want to share what you're watching with your friends, which means you might like Go90's "Cuts" feature that lets you edit a clip from a video and share it with other people within the app. Plus the app's free.

But it's a mobile app. Wouldn't I want to watch TV on my TV?

For millennials, phones and tablets are replacing the TV. According to a 2013 study by Deloitte, 14- to 24-year-olds spend more time watching videos on their computers, phones, tablets and gaming consoles than they do on TV. And non-TV video views are increasingly mobile. According to eMarketer, 51% of the 76 minutes U.S. adults spend on average watching digital videos a day will be spent on tablets and smartphones. And it's also worth mentioning that Verizon operates a large wireless phone business.

So Verizon's using Go90 to get people watching more videos on the go in order to get people to pay more for wireless data?

That would make sense, but Verizon Senior VP of Consumer Product and Marketing Brian Angiolet said that's not the case. "We had never conceived of this being an on-the-go type of thing," he said. Instead Verizon expects people to use Go90 to stream longer videos like full-length episodes of Discovery's "Mythbusters" over wifi while sitting on the couch. "This is a living room application," he said.

But not a connected-TV application?

Not yet at least. The app will initially launch for smartphones and tablets, though Verizon is considering bringing it to other devices in the future, Mr. Angiolet said.

Ok, so what will I see when I first open the app?

A sign-in screen. You'll need to create an account, which means giving Verizon your email address and age as well as creating a profile name for your account. Verizon needs your age to comply with COPPA regulations by making sure people who use the app are at least 13 years of age (of course people can fake their ages, but Verizon can't really do anything about that). And the email address would be a way for Verizon to communicate with its users as well as potentially a way to target ads. Verizon's not ready to talk about that possibility yet, but we'll get to ads later. As for the profile name, you need one for the same reason you would need a Twitter handle. Verizon wants Go90 to be a social video app, meaning that people will be able to follow other users and have videos recommended to them based on who they follow.

OK, then what?

Then you'll be shown between six to eight content categories like comedy and sports. You can click on the categories that you're interested in, which Verizon will use to start filling up your feeds with videos you might want to watch.

Feeds plural?

Yep. Verizon has organized Go90 into four different sections to give you different ways of finding videos to watch. The first one is called "My Feed." This is effectively the app's home page, and it's where you'll find the latest videos from the people and shows you follow. "If you're following [Comedy Central's 'The Nightly Show With Larry Wilmore'], the minute the next episode is updated into the system, it will populate in the feed view," Mr. Angiolet said. The same goes for videos that your friends may have watched and shared within the app. "It's supposed to the most up-to-date things of interest to you. We think people will go that first because it will change most frequently."

So this is where I'll be able to find live programs?

Yes, but you'll also be able to get notifications when a live program is about to start

Ok, so what are the other tabs?

The second one is called "Following." This tab "is basically the closest thing to a more traditional channel guide," Mr. Angiolet said. It's organized into four sections: channels, shows, people and crews. Channels and shows are what you'd expect. If you want to see the content that MTV or AwesomenessTV have uploaded to Go90, you can check out their listings under the channels section. If you want to find older episodes of a specific show, you can check out the shows section.

The "people" section is a bit different. Since you can follow specific actors or actresses, you'll be able to see videos starring those thespians. For example, if you're following Harrison Ford, you can find the latest "Star Wars" trailer.

Additionally you'll be able to see clips that specific friends have edited from videos within the app. Verizon has negotiated content rights so that people can create short "cuts" of videos -- like a funny joke from a Comedy Central show or crazy play from an NFL game -- to share with others. "People are a channel, which for this demo is a really a major insight we have found," Mr. Angiolet said.

And finally there's the "crews" section. A crew is a group of people that fit a certain profile, like Dallas Cowboys fans or urban dads, who share videos related to the crew's description. You can create your own crews or follow crews that others have been created. You can find crews to follow by clicking on a program in the "shows" section, which will display a list of crews following that show.

And that's all in the second tab? Aren't there still two more tabs?

Yes, but the two remaining tabs are pretty basic. The "Profile" tab "is the community's view of you," Mr. Angiolet said, and will display the videos that you've shared. And the "Explore" tab is the Verizon-curated programming guide. There will be a "daily dose" atop the section pointing to programs popular on a given day, like an NFL game or live concert. And Verizon's "playing with" other ways to fill up this feed such as a lists of videos based on the time of day or top videos to discuss around the watercooler.

All of this sounds a lot different from OnCue, the internet TV service that Verizon acquired from Intel that was supposed to reimagine the cable-TV bundle and formed the backbone of Go90. Why the change from full-blown internet TV service to a millennial-focused, mobile video app?

Mr. Angiolet cited two reasons for the change. 1) Acquiring content for a full-blown internet TV service is hard. Intel had tried and failed to sign deals with TV networks and other rights holders to bring their programs onto its service, so Verizon didn't entertain the notion of retreading those steps. "We did not buy OnCue because of the business model," he said. 2) Verizon is trying to future-proof its business.

"We also operate obviously our FiOS TV business, which is a successful pay-TV business. But what we see is that as cord-cutting continues to grow, that is an aging platform," Mr. Angiolet said. "If we wanted to build a product for growth, we wanted to go to a segment that was more open and active and also where we thought there were business problems we could solve, i.e. choice, content breadth, shows not channels and new experiences like social integration."

What's with the "shows not channels" strategy?

Simply put: it's easier to get content rights that way. Instead of signing deals with TV networks to bring their entire content libraries onto Go90, Verizon has cherry-picked individual shows. "We're not taking the whole Viacom bundle. We're taking four channels and two or three shows within those channels," Mr. Angiolet said. And when it comes to live programming like games or concerts, Verizon was able to go to sports leagues or artists directly to secure those rights instead of networks that might try to bundle other programs into a deal. And there's also the idea that millennials typically search for what to watch by querying individual shows and events than channels, he said.

You said earlier that Go90 is a free service. That means it'll have ads, right?

Yep. Mr. Angiolet wouldn't say much about the ads Go90 will carry, though. So stay tuned.