An NFA is defined by the quintuple M = (Q, ∑ , δ, , F)
Q is a finite set of initial states.
∑ is a finite set of symbols called the input alphabet.
Q is the initial state
F ⊆ Q is the set of final states
δ: Q X (Σ ∪ {λ}) → or P(Q)
[It also has input alphabet λ i.e. it has moves for λ]
Language accepted by NFA (M) is the set of all strings accepted by M.