Machine learning is a branch of artificial intelligence that allows computer systems to learn patterns from data rather than depending entirely on manually written rules. Developers train machine learning models using examples so that the models can recognize relationships and produce useful predictions or classifications.

For example, an email service can learn to identify spam, an online store can recommend products based on user activity, and a financial system can detect unusual transactions. These applications use different kinds of data and learning techniques to solve specific problems.

Machine learning is not a single technique. It includes different approaches for learning from labeled examples, discovering patterns in unlabeled data, or learning through feedback. Understanding these approaches helps explain how machine learning systems are developed and where they are useful.