“Many of the CISOs I talk to tell me that “Advanced Persistent Threats” (APT) style attacks are among their top concerns. As I have written about before, the problem with the term APT is that it doesn’t describe this category of threats very accurately. This makes it harder to understand and mitigate this type of threat. At Microsoft we find that a more accurate and useful term for this category of threat is “targeted attacks by determined adversaries”.
See the remainder of the blog post by Tim Rains at http://blogs.technet.com/b/security/archive/2013/06/13/targeted-attacks-video-series.aspx.