Artificial intelligence (AI) refers to the broad branch of computer science focused on creating systems capable of performing human tasks. AI systems can take the form of software (algorithms), hardware (robotic arms on an assembly line), or a combination of both (semi-autonomous vehicles). While the term "artificial intelligence" may inspire images of sentient humanoid robots like those of popular science fiction literature and film, most AI exists as computer systems composed of algorithms and large amounts of data entered by humans. Because they simulate human intelligence, AI systems depend upon human input to acquire skills, knowledge, and reasoning. AI has enabled the automation of many tasks, from grading exams and transcribing spoken words to vacuuming carpets and driving cars.