# Baire theorem explanation

Can someone give an intuitive or geometrical explanation of the Baire category theorem?

Theorem (Baire): Let $(X,d)$ be a complete metric space. For every sequence $\{O_n\}_{n\in\mathbb{N}}$ of open and dense subsets of $X$ the $\bigcap$$_{n\in\mathbb{N}}$$O_n$ is a dense subset of $X$
A set is in a metric space $(X,d)$ is of $second$ $category$ if it is not a union of nowhere dense subset of $X$