A finite automaton is a mathematical model used to represent and analyze the behavior of systems with a limited number of states. It consists of a finite set of states, including one start state and one or more accept states. The automaton processes input symbols from a defined alphabet, transitioning between states based on specific rules. Finite automata can be classified into two types: deterministic finite automata (DFA) and nondeterministic finite automata (NFA). DFAs have a single possible transition for each input symbol in a given state, while NFAs can have multiple transitions for the same input. These models are fundamental in computer science, particularly in compiler design and pattern matching.