Microsoft has joined Google and Facebook in plotting a replacement for the cookie.
For many years the humble cookie, a small text file that browsers download when they visit a web site, has been one of the mainstays of online advertising, allowing advertisers to track users from site to site. However, cookies are unable to track users from device to device, and with almost 20 per cent of browsing now done on mobile devices advertisers are looking for an alternative model.
This is why data-rich internet behemoths such as Google (which many see as an advertising company first and foremost) have been looking at ways of tracking users across a range of devices.
Last month Google announced that it was planning to abandon third-party cookies in favour of an anonymous ID system. User IDs would be shared with advertisers who sign up to Google's plan, allowing detailed targeting but also enabling Google more choice in how much information it parts with and to whom. Few details were made available as to how the system would work, but presumably Google would build user profiles from its Gmail and Google+ properties when subscribers use their accounts to log in to third-party sites, pulling in information such as geo-location to target ads.
Facebook has also been planning for a post-cookie world, in January rolling out a system known as Optimised CPM that makes use of the data Facebook holds on its subscribers to identify users most likely to take an action specified by the advertiser.
Yesterday a Microsoft spokesperson told AdAge that Redmond was thinking along similar lines.
"We agree that going beyond the cookie is important. Our priority will be to find ways to do this that respect the interests of consumers," the spokesperson said.
For Microsoft, which arrived late to the mobile feast, the benefits are obvious. According to a survey by MarketsAndMarkets, the cross-platform and mobile advertising market is expected to be worth $76.57bn (£48bn) by 2018. Along with a range of devices - PCs, tablets and smartphones - that run Windows, the XBox games console, which is also used to stream TV, is likely to be of great interest to advertisers.
While the detail of the plans was not revealed, user profiles could potentially be derived from the use of Microsoft services such as Outlook, Bing and Internet Explorer and used to identify them across devices. This would allow Microsoft to control and manage the information that it makes available to third party advertisers, potentially putting it in a very powerful position.
While advertisers and privacy advocates alike have long expressed a wish to do away with the third-party cookie, whether either will be happy with a situation in which control of vast amounts of behavioural data by a handful of corporate giants is consolidated still further is another thing entirely.