Disney, Fox and Warner Bros. Discovery announced on Tuesday that they would join together and sell access to all of the sports they televised through a new streaming service. It will be available this fall, but many other details, like price or who would run the service, are not yet known.

The subtext of the agreement — and of most decisions media companies make — is that the cable bundle is collapsing. A decade ago, about 100 million homes in the United States subscribed to a package of cable or satellite television channels. Today, that number is around 70 million, and dropping.

Media companies know that young adults no longer sign up for cable, and that their best customers are also their oldest. They know people no longer think of “television,” but are instead used to “content” that can be watched on a television, a phone or some other device.

Cable’s days seem numbered, but right now it is still a profitable business — streaming, for most companies, is not — and the biggest audiences for shows, especially sports, still exist on traditional television. So how do media companies get from where they are today to where they are going to be?

With, they hope, deals like the one announced this week.

How does it work?

Disney, Fox and Warner Bros. Discovery have bundled 14 of their channels that show sports — the full list is ABC, ESPN, ESPN2, ESPNU, SEC Network, ACC Network, ESPNews, Fox, Fox Sports 1, Fox Sports 2, Big Ten Network, TNT, TBS and truTV — and the ESPN+ streaming service, and will sell them as a single package.

How much will it cost?

That was not announced. But you can expect it to cost more than the $15 or so a month that most streaming companies charge, and less than the $100 or so it costs each month to subscribe to a pay television package. Ads will be shown on the new service.

Is this a streaming service or a cable-like bundle of channels?

Both, sort of. It is definitely a streaming service that you will be able to subscribe to and watch on a variety of devices. But rather than a menu of different shows to watch on demand, there will be channels that you can watch live, much as cable customers do.

As a result, this means subscribers to the service will also be able to watch the non-sports shows these channels televise, like “The Simpsons” and “The Bachelor.”

What’s with all the content that’s not sports?

The contracts between networks and leagues are usually specific about where games can be shown. Because of a fear of a smaller audience, most leagues have been hesitant about allowing too many games to move off broadcast and cable channels and shift fully to streaming. But this new service is structured in such a way that it offers everything on the included channels: sports and non-sports content alike. That makes it more like existing cable bundles, and it means the companies did not need to secure permission from the leagues to show the games on the service.

Is this the only service I need to watch all the sports I want?

Nope. Disney, Fox and Warner Bros. Discovery have paid for the right to show a ton of sports, but they don’t own the rights to everything.

NBC, CBS, Amazon and other smaller players are not a part of this agreement. So if you want to watch the sports they have the rights to — which include a lot of National Football League games, golf majors and the PGA Tour, the men’s college basketball tournament, the Olympics, and the English Premier League, among others — you will still have to subscribe to those channels.

So how do I get all the sports?

Well, you subscribe to a pay television package or, in the case of Amazon, Amazon Prime. You can get what is shown on CBS and NBC with a cheap digital antenna, but if you want the games on USA or the CBS Sports Network, you’ll have to get a pay television package. For any games exclusively on NBC’s Peacock streaming service (like this season’s N.F.L. playoff game between Kansas City and Miami) or CBS’s Paramount+ streaming service, you’ll have to subscribe to those.

Will the Disney, Fox and Warner Bros. Discovery channels still be part of normal cable or satellite packages?

Yes.

If I need to subscribe to cable to get sports on CBS and NBC channels, and Disney, Fox and Warner Bros. Discovery channels will be there, too, why bother with this new service?

Intense sports fans may not want to. But this service takes many sports that were available on cable and sells them another way. If you care about all sports, or about non-sports channels like the Food Network or Nickelodeon, it probably isn’t for you.

But if you paid the one-time cost for a digital antenna and then bought this package, you could watch a large percentage of all sports shown on television for a price that is likely much cheaper than a cable subscription.

It could also be worthwhile if you are a fan of only a few sports. Do you like the National Basketball Association? You can get 100 percent of the nationally televised game through this package. Like a smaller college sport, like volleyball? You can get most of it through this package.

This doesn’t sound like a perfect solution.

It probably isn’t. Right now, your options are to pay for a television package (and a handful of streaming services) to watch everything, get a digital antenna and watch the N.F.L. and a few other big events on traditional television, or not watch sports.

One day, you might be able to pay for individual games à la carte, or some service might bundle all of sports together and somehow offer it for a lower price than a cable subscription. This package may serve as a bridge toward that future for some sports fans.

Can you please stop calling it a package?

Blame the companies for not having a name. They’re just calling it a “joint venture.”