Whitespace refers to any blank space that appears on the published version of a Wikipedia page across all namespaces that is free of special characters, templates, media, or other HTML elements. In other words, it appears as empty, white space.
Whitespace is not always desirable. It can give the page an untidy appearance and make the article look incomplete. But it cannot always be avoided, and there are times, when used sparingly, whitespace can enhance readability and visual balance, helping readers to better navigate and absorb the content on the page.