Windows Phone 8 Update 3, formerly known as General Distribution Release 3 (GDR3), is the third and final OS update for the Windows Phone 8.0 operating system before Windows Phone 8.1.
The update has been released-to-manufacturers in September 2013 and a developer-preview version was released on October, 14th 2013. The update is meant to add new features to current devices, in addition to allowing 1080P displays and quad-core processor support (Qualcomm Snapdragon 800) for new hardware.
Update 3 will launch on with the Nokia Lumia 1520 in early November and current Windows Phone 8 devices will receive the update in the coming months. In addition to the OS update, Nokia devices will also receive the Lumia Black firmware update.
Windows Phone 8 Update 3 changelog (OS build 10501, 10512)