A US judge ruled Friday that Apple must allow developers to use their own payment system outside the App Store.

But what exactly is that?

Four questions and answers about the case.

1. What is the case about?

The conflict started in August last year, when Apple


the game


from the App Store.

Many developers who offer apps in the App Store pay Apple 30 percent per sale and keep 70 percent for themselves.

Because Epic thought that percentage was too high, it decided to use its own payment system in


to get around the commission.

That was against Apple's rules, after which the tech




from the App Store.

Epic then accused Apple of monopolistic behavior and took the company to court.

According to the game developers, the 30 percent commission is too high, but developers have no choice, because the App Store is the only way to offer apps to iPad and iPhone owners.

2. What has the judge now ruled?

The judge ruled Friday that Apple must allow developers to use their own payment system, but that only has to be done outside the App Store.

This means that developers are still not allowed to use their own payment systems in their apps, but are allowed to link to a payment option outside of it, for example the developer's website.

The ruling is good news for developers: once the new rules go into effect, they can bypass Apple's 30 percent commission by placing a link to their own website in the app.

It is not yet clear whether the new rules will only apply to game developers or to all types of apps.

Apple expects to get more clarity about this in the coming months.

According to the tech giant, it is also not yet known when the new rules will come into effect.

3. What about the so-called competition law?

Epic Games accused Apple of illegal monopoly behavior, but the judge did not agree.

According to the judge, the game developer has not sufficiently substantiated why there is a monopoly.

Epic stated that the mobile game market is a relevant market and that Apple controls 55 percent of this market.

However, according to the judge, that was not sufficient evidence to conclude that Apple was guilty of monopolistic behavior.

The judge found 55 percent not abnormally high and other parties are also currently taking steps in the mobile game market.

According to the judge, Epic Games should have paid more attention to the subject.

4. How did Apple and Epic Games react to the ruling?

According to Apple, that ruling around monopoly behavior is a "big victory" for the company.

However, the ruling does mean that a big bite is being taken from the profitability of the App Store.

According to analysts, the App Store brings in more than 20 billion dollars (17 billion euros) a year with a profit margin of more than 75 percent.

Epic Games is appealing the ruling. "Today's ruling is not a victory for developers or consumers. Epic fights for fair competition between in-app payment methods and app stores," Epic Games CEO Tim Sweeney wrote on Twitter on Friday.