For much of its life, the site has done both of these things. It has allowed hundreds of thousands of people to publish their thoughts, including celebrities such as President Barack Obama. But at the same time, it has also created its own in-house publications, like the science magazine Matter (which it acquired) and the tech site Backchannel.

Recently, however, there have been signs that Medium would like to be more of a hosted service and less of a custom publisher. In one recent step, for example, the site announced that Matter is being spun off as a standalone service and will become a kind of media incubator that is owned by Williams and run by Medium’s former head of editorial, Mark Lotto.

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In an interview this week, Williams gave one of the clearest indications yet that he sees the site’s future as being a content-agnostic hosting service for publishers of all kinds. He talked about the deal that Medium recently announced with The Ringer, a new venture from former Grantland publisher Bill Simmons, where Medium essentially functions as the website for The Ringer and any content gets published through it.

That’s really the next phase for Medium—to empower professional publishers—and The Ringer is part of that effort. And the reason that we were able to get that deal is, basically, they saw that we were sort of the next generation beyond building or managing an out-of-the-box CMS. They got all of the advantages of that, plus a network that they could tap into.

Williams goes on to say that the “magazines” the site helped create, such as Backchannel, were effectively experiments designed to showcase what Medium was capable of as a host, to help convince publishers to come on board. A number of in-house publications—including The Nib, Re:form and The Message—have either been shut down or restructured over the past year.

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“The publications were always an opportunity for us to learn more about our platform, as well as to rolemodel what other publications can do,” Williams told Ad Age. “In talking to The Ringer and others, having these professional publications on the platform helped a lot in making those deals. But long-term it’s clearer and clearer I think to the world that Medium really is a platform, and there may be flagship publications that we own, but that’s not the gist of it.”

This confirms what sources close to the company have been saying for some time, which is that it is de-emphasizing Medium’s in-house publications and focusing on hosting content produced by other publishers. Insiders say the site is hoping to compete with publishing tools like WordPress, which powers the sites of some of the Internet’s largest publishers. In an interview last fall San Francisco, Williams said that platforms are the future of media.

Medium’s new focus holds the potential for growth, but it also puts the company directly in the path of Facebook, since the giant social network is also busy trying to convince publishers large and small to see it as a home for their content—a distribution platform that can help get their journalism in front of more than a billion people.

Already, sites like the Washington Post and Mic are publishing 100% of their content through Facebook’s mobile-focused Instant Articles project, and the social network recently opened the feature to anyone, large or small. According to the Post, being part of the project has already translated into significant traffic and audience gains for the newspaper, which recently bragged about having more unique visitors than BuzzFeed.

One of the things that could help Medium differentiate itself, at least in the short term, is support for paywalls and other ways for publishers to make money. Williams has said a number of times that the site is working on such features, as well as support for native advertising, and hopes to roll them out to publishing partners soon.