Optional Update Will Prompt Windows 7 And 8.1 Users To Upgrade To Windows 10
Windows Update KB3035583 is a recommended update, which makes it essentially optional – you’ll need to select the update to install it. Microsoft describes KB3035583 purpose as enabling “Additional capabilities for Windows Update notifications in Windows 8.1 and Windows 7 SP1.”
According to Myce, which appears to be the first to post details about the Windows 10 prompt, the update adds a folder called GWX that has several .EXE files. One of those appears to be a notification tool that could display banners and other ads for Windows 10 as the launch date approaches.

Microsoft is expected to launch Window 10 this summer and has already said that it will allow free upgrades to the new operating system for the first year.