Short Definition
Machine learning is a way of building software systems that learn patterns from data instead of relying only on hand-written rules.
Intuition
A traditional program follows rules written by a developer. A machine learning model is trained from examples, then uses the learned pattern to make predictions on new inputs.
Technical Definition
Machine learning studies algorithms that fit parameterized functions to data by optimizing an objective such as prediction accuracy, likelihood, or expected reward.
Example
A spam classifier learns from labeled emails and predicts whether a new message is spam.
Common Misunderstandings
Machine learning is not the same thing as artificial intelligence.
A model does not understand data just because it predicts labels well.