Microsoft recently released their semi-annual major update to the Windows 10 operating system. The update is known as CU 1803 and can take a substantial amount of time to install, depending on the speed of your Internet connection. It may also restart your computer several times, so be patient when installing!
You can always chck your current version of Window 10 by clicking on the Start button, clicking on the “gear icon” for Settings, clicking System in the upper left corner of the screen and then selecting About, at the bottom of the menu on the left. You should see something similar to this: