Prolog is a high-level programming language primarily used for artificial intelligence and computational linguistics. It is based on formal logic, allowing programmers to express facts and rules about problems within a system. Prolog uses a unique approach called "declarative programming," where the programmer specifies what the program should accomplish rather than how to achieve it. In Prolog, programs consist of a series of logical statements, which can be queried to derive conclusions. This makes it particularly effective for tasks involving pattern matching, natural language processing, and knowledge representation. Its ability to handle complex relationships and reasoning makes it a valuable tool in various AI applications.