A Concise Explanation of Learning Algorithms with the Mitchell Paradigm by Matthew Mayo via @kdnuggets

A single quote from Tom Mitchell can shed light on both the abstract concept and concrete implementations of machine learning algorithms:

A computer program is said to learn from experience E with respect to some class of tasks T and performance measure P, if its performance at tasks in T, as measured by P, improves with experience E. 
- Tom Mitchell, "Machine Learning"

I really like this thoughtful and clear article discussing the quote form Tom.