Working memory is a cognitive system that temporarily holds and manipulates information needed for complex tasks such as learning, reasoning, and comprehension. It allows individuals to keep relevant information in mind while performing mental operations, like solving a math problem or following multi-step instructions. This type of memory is limited in capacity, typically holding about 7 items at once, as suggested by George A. Miller's research. Working memory is crucial for everyday activities, such as remembering a phone number long enough to dial it or keeping track of a conversation's context.