Windows Defender has offered a baseline level of PC security for years, but that's not really going to cut it in an era when data breaches and other large-scale cyberattacks are virtually commonplace. That's why Microsoft is stepping up its game: it's launching Windows Defender Advanced Threat Protection, an optional Windows 10 enterprise service that flags signs of cyberattacks in time to prevent a bad situation from getting much worse. It looks for telltale clues on individual PCs, such as exploit attempts and unusual system file access. If something's up, it'll recommend a response to the IT staff -- they may not have to sift through activity logs to know what's causing grief on their network.
ATP is already in use by a few early adopters right now, and it'll be more broadly available later in 2016. You probably won't see how this works unless you're managing a network, but it could make a big difference in your life if you've ever been notified of a compromised bank account or health care file. Instead of waiting months for the company to even realize that there was a problem (long after fraudsters have a field day), you could get a heads-up much sooner. That, in turn, could speed up the fix and reduce the chances that someone raids your sensitive info.