Photosynth is a service created by Microsoft Live Labs and the University of Washington. It stitches multiple photos together in order to create a 360-degree panorama, allowing users to share their world in 3D with friends.
Originally launched in November 2006, Microsoft has announced that 10 years on, it is now retiring the Photosynth service. On February 6, 2017, the company will shut down the website used to access the service.
To ensure that users don't lose their synths, Microsoft has created a viewer whereby users will always be able to view their synths offline on their PCs (Windows or Mac). Data that is on the site will be permanently deleted once the site is shut down.
Microsoft's Photosynth team claim that the service was not used by enough people to warrant the continued investment and instead noted that they are "committed to development efforts in the experiences that mean the most to our customers".
For information on how to use the offline viewer and to read Microsoft's announcement, see here.