Which of the following is a characteristic of Metadata?

Metadata is defined as data that provides information about other data. This can include details such as the content type, author, date created, and other attributes that describe the characteristics of the main data. In the context of web development, metadata is often found in HTML documents as meta tags within the head section, where it can describe the contents of a webpage or provide information for search engines.

The other options do not accurately describe metadata. While visual elements of a webpage pertain to the design and layout, they do not provide additional information about the data itself. Furthermore, metadata is not always visible to the user, as it primarily serves the purpose of informing systems (like search engines) or developers rather than being part of the user interface. Lastly, metadata is not a programming language; rather, it can be expressed through various formats and languages but is fundamentally about describing data rather than executing code.