If you have Apple's QuickTime installed on your Windows machine, which you probably do if you've installed iTunes before, you should probably uninstall it unless you have a really valid reason for running it. Why?
On April 14, Trend Micro posted that they discovered two zero-day security vulnerabilities in the Windows version of QuickTime. Trend Micro then went on to report that Apple was not going to patch these vulnerabilities. The Department of Homeland Security then also recommended that Windows users should uninstall QuickTime.
On April 18, Apple officially confirmed that it has stopped support for QuickTime on Windows, however you can still download it on Apple's site. Apple has not updated QuickTime for Windows since January 2016 with version 7.7.9.
In order to uninstall QuickTime, all you have to do is uninstall it like you would with any other Windows program. All you have to do is open the Control Panel, and navigate to the Programs and Features. Scroll down and find QuickTime Player, and click it once and then click the Uninstall button and follow the instructions on screen.
If you are looking for a good alternative to QuickTime, I would suggest VLC media player from VideoLAN. QuickTime on the Mac is unaffected!