Artificial intelligence (AI) is the mimicking of human thought and cognitive processes to solve complex problems automatically. AI uses techniques for writing computer code to represent and manipulate knowledge. Different techniques mimic the different ways that people think and reason (see case-based reasoning and model-based reasoning for example). AI applications can be either stand-alone software, such as decision support software, or embedded within larger software or hardware systems.
AI has been around for about 50 years and while early optimism about matching human reasoning capabilities quickly has not been realized yet, there is a significant and growing set of valuable applications. AI hasn't yet mimicked much of the common-sense reasoning of a five-year old child. Nevertheless, it can successfully mimic many expert tasks performed by trained adults, and there is probably more artificial intelligence being used in practice in one form or another than most people realize.
Really intelligent applications will only be achievable with artificial intelligence and it is the mark of a successful designer of AI software to deliver functionality that can't be delivered without using AI. See quotations

This definition is in context to Artificial Intelligence. See more contextual defintions for Artificial Intelligence.