Why is proper markup essential for documents?

Proper markup is fundamental for documents because it ensures that assistive technologies can interpret the information accurately. When a document is correctly marked up, it means that the structure and semantics of the content are well-defined. This is crucial for users who rely on screen readers and other assistive devices to access information.

With appropriate markup, elements such as headings, lists, tables, and links are correctly identified, allowing assistive technologies to convey the organization and meaning of the content effectively. This arrangement enables users with disabilities to navigate, understand, and interact with the document in a way that aligns with their varied needs.

The other options, while they may pertain to documents in some contexts, do not capture the primary role of proper markup in ensuring accessibility. For instance, the appearance or performance aspects of a document may be improved, but these are secondary to the essential goal of making content comprehensible to all users, particularly those with disabilities.