What is learning: learning is any process by which a system improves perfomance from experience - Herbert Simon
Machine Learning is study of algorthms that improve the performace P at some task T with experience E.
well defined learning task < P, T, E >
Machine learning (ML) is the scientific study of algorithms and statistical models that computer systems use to perform a specific task without using any explicit instructions, relying on patterns and inference instead. It is a subset of artificial intelligence. Machine learning algorithms build a mathematical model based on sample data, known as "training data", in order to make predictions or decisions without being explicitly programmed to perform the task. Machine learning algorithms are used in a wide variety of applications, such as Handwritten Digit Recognition, email filtering and computer vision, where it is difficult or infeasible to develop a conventional algorithm for effectively performing the task.
Machine learning is closely related to computational statistics, which focuses on making predictions using computers. The study of mathematical optimization delivers methods, theory and application domains to the field of machine learning. Data mining is a field of study within machine learning, and focuses on exploratory data analysis through unsupervised learning. In its application across business problems, machine learning is also referred to as predictive analytics.