There are many deep definitions of statistical machine learning, but let's start off with the simplest or most basic version:
Machine learning is the process that aims to teach a computer to make realistic predictions (or improve on predictions) based on some flow or source of data.
The reader should take note that the data source explicitly depends upon the problem the data scientist is solving (trying to solve). For example, the subscription entertainment service Netflix would not use patient dental record data as input in an attempt to predict subscriber viewing behaviours!
An explanation that's a little deeper can be provided:
Machine learning is a sub-field of computer science that evolved from the study of pattern recognition and computational learning theory in artificial intelligence. In 1959, Arthur Samuel defined machine learning...