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# Difference between DFA and NFA

• Difficulty Level : Easy
• Last Updated : 26 Feb, 2021

Prerequisite – Finite Automata

1. DFA :
DFA refers to Deterministic Finite Automaton. A Finite Automata(FA) is said to be deterministic, if corresponding to an input symbol, there is single resultant state i.e. there is only one transition.
A deterministic finite automata is set of five tuples and represented as, Where,
Q: A non empty finite set of states present in the finite control(qo, q1, q2, …).
Σ: A non empty finite set of input symbols.
δ: It is a transition function that takes two arguments, a state and an input symbol, it returns a single state.
qo: It is starting state, one of the state in Q.
F: It is non-empty set of final states/ accepting states from the set belonging to Q.

2. NFA :
NFA refers to Nondeterministic Finite Automaton. A Finite Automata(FA) is said to be non deterministic, if there is more than one possible transition from one state on the same input symbol.
A non deterministic finite automata is also set of five tuples and represented as, Where,
Q: A set of non empty finite states.
Σ: A set of non empty finite input symbols.
δ: It is a transition function that takes a state from Q and an input symbol from and returns a subset of Q.
qo: Initial state of NFA and member of Q.
F: A non-empty set of final states and member of Q.

Difference between DFA and NFA :

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