Definition 7.6.3.1. Let $\operatorname{\mathcal{C}}$ be an $\infty $-category and let $\sigma : \Delta ^1 \times \Delta ^1 \rightarrow \operatorname{\mathcal{C}}$ be a commutative square. We say that $\sigma $ is a pullback square if it is a limit diagram in $\operatorname{\mathcal{C}}$ (see Definition 7.1.2.4), and that $\sigma $ is a pushout square if it is a colimit diagram in $\operatorname{\mathcal{C}}$.
$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$