Websites are basically text documents formatted with what language?

Websites are fundamentally constructed using HTML (Hypertext Markup Language), which serves as the backbone for content structure on the web. HTML allows developers to create and format text documents by using various elements and tags, such as headings, paragraphs, links, images, and lists. This markup organizes the content so that web browsers can render it visually for users.

While CSS (Cascading Style Sheets) is essential for styling the appearance of HTML documents, it does not structure the content itself. JavaScript is primarily used to add interactivity and dynamic behavior to web pages but also does not structure the document. XML (eXtensible Markup Language) is designed for data storage and transport rather than for formatting web pages, thus it doesn't fulfill the role of formatting web content directly for browsers in the way HTML does. Therefore, the fundamental role of HTML establishes it as the correct answer in the context of formatting text documents for websites.