How to show that the diagonal of $X\times X$ is diffeomorphic to $X$?

Question

The diagonal $Q$ in $X\times X$ is the set of points of the form $(x,x)$. Show that $Q$ is diffeomorphic to $X$, so $Q$ is a manifold if $X$ is.

Can anyone please help me to solve this question I have been trying to solve it since two days but I could not.

Thanks.