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 language theory is essential in areas such as compiler design, automata theory, and programming languages, as it helps in understanding how languages can be constructed and processed. The theory categorizes languages into different classes, such as regular languages, context-free languages, and context-sensitive languages, based on their complexity and the types of grammars that generate them. Each class has unique properties and applications, influencing how computers interpret and execute code. Understanding these classifications aids in the development of algorithms and tools for language processing.