Source: wikibot/second-countable-space
= Second-countable space
{wiki=Second-countable_space}
In topology, a **second-countable space** is a type of topological space that has a specific property related to its basis. A topological space \\(X\\) is said to be second-countable if it has a countable basis for its topology. More formally, a **basis** for a topology on a set \\(X\\) is a collection of open sets such that every open set in the topology can be expressed as a union of sets from this basis.