Machine learning is behind many of today’s most powerful artificial intelligence systems, from search engines to self-driving cars.

Machine learning is a way of teaching computers to do tasks. In the past, to do anything computers relied on detailed, step-by-step instructions written by a person. But with machine learning, computers pick up new skills on their own, using examples or experience. This makes machine learning a powerful form of artificial intelligence, or AI. AI is the ability of a machine to think or learn like a person. AI systems power many kinds of machines — from smartphones to robots.

There are a few types of machine learning. The most common is supervised learning. In this method, a computer is fed lots of labeled training data. For instance, it may look at many photos of dogs. Each photo might be labeled with the dog’s breed. By studying those photos, the computer learns what each breed looks like. Then, the computer can pick out dog breeds in new, unlabeled photos. The more data the computer studies, the better it gets at its task.

Another important kind of machine learning is reinforcement learning. Using this type of learning is sort of like training your dog to do a trick. The computer learns to achieve some goal by interacting with its environment. When the computer makes a choice that brings it closer to its goal, it gets a virtual reward. Through trial and error, the computer learns to make better choices. This type of machine learning has helped computers master difficult games like Go and StarCraft II. It has also been used to teach self-driving cars how to get around.

Machine learning has helped create technology all around us. It powers language translators and search engines. When your streaming services recommend new shows you might like, that’s machine learning at work. Machine learning systems also organize posts in social media feeds. They even help diagnose diseases. In many ways, the problem-solving power of machine learning is reshaping the world.

Machine learning and other types of artificial intelligence are behind computer-made artwork. 

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artificial intelligence: A type of knowledge-based decision-making exhibited by machines or computers. The term also refers to the field of study in which scientists try to create machines or computer software capable of intelligent behavior.

data: Facts and/or statistics collected together for analysis but not necessarily organized in a way that gives them meaning. For digital information (the type stored by computers), those data typically are numbers stored in a binary code, portrayed as strings of zeros and ones.

diagnose: To analyze clues or symptoms in the search for their cause. The conclusion usually results in a diagnosis — identification of the causal problem or disease.

engine: A machine designed to convert energy into useful mechanical motion. Sometimes an engine is called a motor. (in computer science) A computer program that performs a particular, narrow range of functions.

environment: The sum of all of the things that exist around some organism or the process and the condition those things create. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature and humidity (or even the placement of things in the vicinity of an item of interest).

intelligence: The ability to collect and apply knowledge and skills.

machine learning: A technique in computer science that allows computers to learn from examples or experience. Machine learning is the basis of some forms of artificial intelligence (AI). For instance, a machine-learning system might compare X-rays of lung tissue in people with cancer and then compare these to whether and how long a patient survived after being given a particular treatment. In future, that AI system might be able to look at a new patient’s lung scans and predict how well they will respond to a treatment.

reinforcement: Some consequence that guides the future behavior of an animal or person. If a rat presses a lever and receives a food pellet, that food pellet becomes a reinforcement of lever-pushing — it’s the reward that will teach the rat to press the lever again.

reinforcement learning: An approach to teaching in which an animal or a person learns to perform a specific task to achieve a desired reward.

reward: (In animal behavior) A stimulus, such as a tasty food pellet, that is offered to an animal or person to get them to change their behavior or to learn a task.

search engine: (in computing) A computer program that allows a computer to search for information on the Internet. Common examples include Google, Yahoo and Bing.

self-driving car: Also known as a driverless car or autonomous vehicle. These cars pilot themselves based on instructions that have been programmed into their computer guidance system.

social media: Digital media that allow people to connect with each other (often anonymously) and to share information. Examples include Twitter, Facebook, Instagram, TikTok and WhatsApp.

system: A network of parts that together work to achieve some function. For instance, the blood, vessels and heart are primary components of the human body's circulatory system. Similarly, trains, platforms, tracks, roadway signals and overpasses are among the potential components of a nation's railway system. System can even be applied to the processes or ideas that are part of some method or ordered set of procedures for getting a task done.

technology: The application of scientific knowledge for practical purposes, especially in industry — or the devices, processes and systems that result from those efforts.

virtual: Being almost like something. An object or concept that is virtually real would be almost true or real — but not quite. The term often is used to refer to something that has been modeled — by or accomplished by — a computer using numbers, not by using real-world parts. So a virtual motor would be one that could be seen on a computer screen and tested by computer programming (but it wouldn’t be a three-dimensional device made from metal). (in computing) Things that are performed in or through digital processing and/or the internet. For instance, a virtual conference may be where people attended by watching it over the internet.

Maria Temming is the assistant editor at Science News for Students. She has bachelor's degrees in physics and English, and a master's in science writing.

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