Machine Learning, Introduction

What is Machine Learning?

Arthur Samuel once said:
Machine Learning is the field of study that gives computers the ability to learn without being explicitly programmed.
This is an ambiguous definition, but it is one of the most famous definitions so far.

A more precise machine learning definition was given by Tom Mitchell:

A computer program is said to learn from experience E with respect to some task T and some performance measure P if its performance on T as measured by P, improves with experience E.




In more natural terms: A computer program is said to learn to do a task from any experience if its performance on the task improves with experience. The same definition applies to humans learning from experience, isn't it?


Let us consider an example of movie recommendation:
A computer is said to learn movie recommendation with experience (your movie preference) if with more experience it gives better movie recommendations.