Source: Facebook.

That was fast! Less than a month after Facebook (NASDAQ:FB) said it would start expanding Instant Articles to more users and publishers, the social network expanded the feature to all iPhone users and started beta-testing it with Android users. Additionally, Facebook is expanding its publisher partnerships with about 50 new publications.

Instant Articles represents a significant opportunity for Facebook to increase the amount of time spent on Facebook and monetize its publishing partners' content at the same time. This expansion also represents a major threat to Alphabet (NASDAQ:GOOG) (NASDAQ:GOOGL) and its Google advertising tools.

Keeping users on Facebook
Instant Articles accomplishes two things. First, it speeds up load times for the growing number of articles users post to their News Feeds. That reduces abandonment rates for articles and for the app in general. As a result, people spend more time in the app and actually reading the content from publishers -- both parties win.

Second, Facebook takes 30% of any ad space it fills on publishers' behalf in Instant Articles. This positions it to take share away from Google's AdWords and AdMob in fulfilling small publishers' ad inventory. While most of Facebook's early partners are capable of filling their own ad inventory, the potential growth of Instant Articles sets up Facebook to start capitalizing from its content distribution capabilities.

Publishers currently have to apply to create Instant Articles, but the quick expansion from nine publishers to 30 to 80 indicates that Facebook is seeing a lot of applications. As more publishers start creating Instant Articles, it creates a domino effect because no publisher wants the competition to have an unfair advantage.

The rapid expansion also indicates that the past month of testing with about two dozen additional publishers has gone extremely well. That bodes well for the wider audience and how publishers will respond going forward with the full rollout on iPhone and the upcoming Android rollout, expected to be completed by the end of the year.

Advertisers win, too
Facebook's Instant Articles provide a nice user experience and increase readership for publishers, but another big winner is advertisers. Facebook began testing a new ad format it's now calling Canvas ads this summer. Canvas ads work exactly like Instant Articles, except instead of loading an article in one-tenth of a second, it loads an immersive website with product details, images, videos, and sales copy.

As Instant Articles expand, so, too, should Canvas ads. Since users will be used to the immersive experience of Instant Articles, they should respond well to the similar experience found in Canvas ads. That should enable Canvas ads to convert well, increasing the value they provide for advertisers and Facebook.

At the same time, they represent another threat to Google's advertising business. Canvas ads open up the equivalent of entire websites within Facebook. As a result, some marketers may prefer them over search advertising on Google, which is one of the easiest ways to direct people to a website.

Google isn't just standing still
Google recently unveiled Accelerated Mobile Pages, or AMP, which allows publishers to tap into a shared library of code, reducing the amount of code necessary to create a website and consequently speeding up load times. AMP is an open-source alternative to mobile publishing solutions such as Instant Articles.

Google has a strong interest in keeping the Web open. Its Web crawlers can't find articles published solely through proprietary platforms such as Instant Articles. Additionally, Google isn't capable of supplying ads for publishers on those platforms. AMP currently only supports Google's ad tools, but since it's open-source, it could support other ad tech in the future. Still, it requires a lot more work for publishers to get things working for the ad tech they're used to, while Facebook actively worked with several publishers to make Instant Articles work for them.

The rapid expansion of Instant Articles represents a significant threat to Google, indicating that the response from both users and publishers has been very good. For Facebook, it represents an opportunity to start monetizing more of the content it distributes to its 1.5 billion users while keeping them engaged for longer periods of time.

Adam Levy has no position in any stocks mentioned. The Motley Fool owns shares of and recommends Alphabet (A and C shares) and Facebook. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.