Machine learning is reshaping security

At the recent RSA Conference it was virtually impossible to find a vendor that was not claiming to use machine learning. Both new and established companies are now touting "machine learning" as a major component of the data science being used in their products. What the heck is machine learning anyway? And is it really going to reshape cyber security in 2016? For brevity's sake, I'll define machine learning as the science of getting computers to act without being explicitly programmed.