Let $X_1, X_2, \ldots$ be i.i.d. real-valued random variables with $\mathbb{E}[X_i] = \mu$ and $\operatorname{Var}(X_i) = \sigma^2 < \infty$. Then \begin{align*} \sqrt{n}\,(\bar{X}_n - \mu) \xrightarrow{d} \mathcal{N}(0, \sigma^2) \quad \text{as } n \to \infty, \end{align*} where $\bar{X}_n = \frac{1}{n} \sum_{i=1}^n X_i$.