Let’s start with a killer that took root in Windows 8, but blossomed in Windows 10.
Microsoft began baking Windows Defender -- its in-house antivirus solution -- into Windows 8, but that integration contained a fatal flaw. In a bid to toss PC makers a bloatware bone, Microsoft allowed them to disable Defender and include third-party AV trialware instead. The problem? You had to manually reactivate Windows Defender when that trial was up or risk your computer being vulnerable.
Not in Windows 10. Now, Windows Defender automatically reactivates whenever you don’t have another AV solution active. And there’s little need to: while Defender doesn’t come out tops in independent AV tests, it still performs more than well enough for everyday use.