Artificial intelligence (AI) is the simulation of human intelligence by machines, especially computer systems. It involves learning, reasoning, problem solving, perception, and language understanding. The history of AI began with ancient myths but formal development started in the mid-20th century. After initial optimism, AI faced skepticism in the 1970s-80s but has since experienced a renaissance with advances in machine learning and neural networks. AI has applications in healthcare, finance, transportation, customer service, and more. Key techniques include machine learning, deep learning, natural language processing, and computer vision. Ensuring AI's ethical development and addressing challenges like bias, privacy, transparency, reliability, and safety will be important moving forward.