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Google uses a machine-learning artificial intelligence (AI) system called “RankBrain” to help sort through its search results and find the ones deemed most relevant for particular searches. Hummingbird is the overall search algorithm, think of a car’s overall engine. The engine itself is made up of various parts, with RankBrain being one of the newest. In practice, AI is used to refer to computer systems that are designed to learn and make connections. Machine learning is a computer science that uses statistical techniques to give computer systems the ability to "learn" with data, without being explicitly programmed. In terms of RankBrain, AI and machine learning seem synonymous.