# Why aryl halides are very less reactive towards nucleophilic substitution reactions? [duplicate]

I've often herd that aryl halides are very less reactive towards nucleophilic substitution reactions. One of the reasons for this I found was that there is resonance effect in the compound, but how is that responsible for it to less reactive towards S.N. reactions and in addition to resonance effect are there other factors also responsible ?

• $\ce{S_{N}2}$ is impossible since inversion would give an incredibly weird strained ring (even more weird than a bridgehead carbon that is already forbidden by Bredt's rule).
• $\ce{S_{N}1}$ would leave a very unstable empty $\ce{sp^2}$ orbital. This can happen, but only for the very best leaving groups, like $\ce{N2}$.