Windows 10 build 10558 features several new, beautiful Lock screen backgrounds. As you might be knowing, Windows 10 allows the user to set a custom background for the Lock screen. In Windows 10 build 10558, new images are available to be used this way.
Windows 10 build 10558 brought new fancy icons and lots of new features including Windows Spotlight. Windows Spotlight is a feature which was in pre-RTM builds of Windows 10 but dropped in the "RTM" build which was 10240. It downloads beautiful images from the Internet and shows them on your lock screen. So, every time you boot or lock Windows 10, you will see a new lovely image.
We already posted a huge collection of Spotlight images which were available for Windows Insiders in pre-RTM builds. Once you install Windows 10 build 10558, it will download several new images. These images are also very nice: