What is the difference between DFA and PDA?

A Deterministic Finite Automaton (DFA) is a theoretical machine used in computer science to recognize regular languages, where each state has exactly one transition for each input symbol, making its behavior predictable and deterministic. In contrast, a Pushdown Automaton (PDA) is a more powerful machine that can recognize context-free languages; it includes a stack as an additional memory structure, allowing it to handle nested structures and perform more complex computations. While DFAs cannot use memory beyond state transitions, PDAs can manipulate their stack, enabling them to parse certain patterns that DFAs cannot.