We know that any closed manifold $X$ can be embedded into some Euclidian space $\mathbb{R}^n$ for sufficiently large $n\in \mathbb{N}$. What is the easiest way to see this fact? I have seen several proofs but I keep forgetting them.
My motivation to ask this is the fact that any vector bundle $E\rightarrow X$ can be embedded in some trivial bundle $\mathbb{R}^n\times X\rightarrow X$. Any embedding $X\subset \mathbb{R}^n$ is sufficient to prove this.