XML

XML uses nested elements and attributes and is used in formats and protocols including SVG, RSS and various configuration or data-exchange systems. In practical terms, XML belongs to the browser, server or document layer. Knowing that layer is important because it tells you what the term can change, what it cannot change, and where to look when something behaves unexpectedly.

The common mistake is to use XML as if it also meant JSON. That blurs two separate decisions and usually sends troubleshooting in the wrong direction. A better test is practical: Confirm the document is well-formed and that namespaces and element names match the consuming specification.

In day-to-day work, XML matters when the concept needs to be identified precisely instead of being grouped with a nearby term. The practical value is not the vocabulary itself; it is being able to identify the right control, file, setting or decision when the concept becomes relevant.

An XML sitemap uses nested elements such as <url> and <loc> to describe pages in a structured, machine-readable document. That example is useful because it turns the definition into something you can recognize, test and discuss with other people working on the same project.

Use these references when you need documentation-level detail, specifications or product-specific behavior beyond the plain-English explanation above.