MSN, Microsoft's web portal and the default homepage for the Internet Explorer browser, announced on Tuesday it has signed a multi-year deal with content recommendation platform Taboola.

Neither company would comment on the size of the deal, but it will see Taboola take over the content recommendations on MSN in the 50 markets in which it operates. If you browse MSN.com today, you'll see Taboola content recommendations from publishers and advertisers right at the top of the homepage, and within articles. They're tailored to each user, so it's unlikely any two users would see the same homepage.

MSN has also taken on Taboola's "audience exchange product," which will see its technology used to predict which Microsoft services should be promoted to users. So a user browsing MSN on a Windows 8 device might be served an ad prompting them to upgrade, whereas an Android user might be pointed towards downloading Windows apps.

An example of an app recommendation powered by Taboola on MSN. Taboola

In addition, MSN's editors will be taking up Taboola's Newsroom product, which allows them to live-test different content, creative, and placements to different sets of users to see which performs best (known as A/B testing.)

The deal is interesting for a few reasons.

It's another landmark in the evolution of MSN

Once a site devoted to original content from its in-house journalists, MSN made the decision in 2014 to curate content from more than 1,000 other sites such as Business Insider, The Guardian, and Associated Press instead. Terry Myerson, Microsoft's Windows boss then won an internal battle to ensure MSN was primarily used to promote the Windows operating system (rather than becoming the default page for its Bing search product.)

In June last year, Microsoft announced it was handing over all the direct-sales of ads on MSN to AOL, while ad tech company AppNexus would sell the programmatic ads on the site.

Taboola has now become the main source of content recommendation and personalization on MSN (Microsoft still has smaller deals with other partners like Outbrain, but Taboola will power the majority of content recommendations on MSN, plus offering the additional personalization and exchange products.) Microsoft is handing off more responsibility for revenue generation on MSN to a third-party in order to concentrate on using the website to promote its products.

MSN is nothing like the news site it once was. A source close to Microsoft told Business Insider in 2014 that "Microsoft really doesn't care about [MSN]" and suggested the company could be close to shutting it down. In September last year, Microsoft announced a big deal with Chinese internet company Baidu to become Windows' default home page in its browser instead of MSN in the region.

Microsoft is using every web asset it can (through partnerships if needs be) to promote Windows products. MSN still has a huge audience — 52 million unique visitors in November, according to Millward Brown's Compete.com analytics service (see chart below) — that it can market Microsoft products to.

The priority with MSN has shifted from making money from selling other people's ads (which it still does via AOL and AppNexus,) to making money by promoting its own assets.

It could help drive MSN's profitability

Speaking to Business Insider, Joe Cepollina, Microsoft principal program management lead for the Windows Universal Store, said MSN has increasingly become a "strategic product" for Microsoft because it drives users its other products and services.

Cepollina said: "Over the last 12 months [MSN has been] a profitable offering, since we turned over the product strategy and it became part of a broader organization known as the Windows Universal Store. It's in a very strategic place at this point in time and doing a great job in helping drive the Microsoft brand. We probably, definitely, couldn't have said the same 18 months ago."

Cepollina wouldn't comment on how many staff MSN has, but it's clear that the decision not to focus on original content and to outsource advertising to third-parties will have led to some efficiencies.

This is huge for Taboola

This partnership marks one of the biggest (if not the biggest) deal in 9-year-old Taboola's history. The size of MSN's audience means Taboola will now become the number one syndicated advertising platform in the US in terms of reach, Taboola CEO Adam Singolda predicts. In November, Taboola was number two in terms of reach in the US, behind Google.

Compete.com

What's also interesting for Taboola is that it won the bulk of the MSN business as the result of a competitive pitch, which Cepollina said had been ongoing for around five or six months.

While MSN will still continue using a number of other partners in this area — including Outbrain, which will continune its long-running deal to offer content recommendation on some areas of the MSN site — winning business from competitors will see Taboola boosting its market share. And the more reach and publisher partners Taboola has, the more powerful its new business pitch is to advertisers and future publisher partners.

In addition, Cepollina said the partnership also helped Taboola develop better products: "One of the core benefits of working with Taboola was their empathy and willingness to partner with us like part of the development team. They understand our business objectives and worked with us closely and iteratively to come up with solutions that didn't just play to their core product strengths, but really extended their product strengths."