> [!definition] > > Let $X$ be a [[Topological Space|topological space]], then $X$ has the **Lindelof** property if every [[Open Cover|open cover]] has a countable subcover. > [!definition] > > Let $X$ be a topological space, then the following are sufficient conditions for $X$ to be a Lindelof space: > - $X$ is [[Second Countable|second countable]]. > - $X$ is $\sigma$-[[Sigma Compact|compact]].