Formal Language Theory is a branch of computer science and mathematics that studies the syntax and semantics of formal languages. These languages are defined by specific rules and symbols, allowing for precise communication and manipulation of information. Formal languages are essential in various fields, including computer programming, linguistics, and automata theory. The theory categorizes languages into different classes, such as regular languages, context-free languages, and context-sensitive languages. Each class has its own set of rules and properties, which help in understanding how languages can be generated and recognized. This framework is crucial for designing compilers, interpreters, and other computational systems.