Which tag is used to mark off self-containing text in HTML?

The article tag in HTML is specifically designed to represent a self-contained piece of content that could theoretically stand on its own. This could be a news article, a blog post, or any other independent content that makes sense outside of the context it's being presented in.

By using the article tag, developers can provide semantic meaning to the content, which is beneficial for search engines and accessibility tools that rely on the structure of the HTML to understand what the content is about. The use of the article tag enhances the overall organization of the webpage, allowing better navigation not just for users, but also for web crawlers that index the content.

In contrast, the anchor tag is primarily used for creating hyperlinks, the div tag serves as a generic container for grouping elements without a specific semantic meaning, and the aside tag is intended for content that is tangentially related to the main content, such as side notes or supplementary information. Therefore, the article tag is the most appropriate choice for marking off self-containing text in HTML.