XML glossary: the essential terms explained

The terms that come up when working with XML files, defined simply. Useful to understand your product feeds, sitemaps and catalog exports before editing them in a spreadsheet.

XML

XML (eXtensible Markup Language) is a text file format that structures data with nested tags, e.g. <product><price>19</price></product>. It is machine-readable and used as a standard exchange format between software (e-commerce feeds, catalog exports, sitemaps, RSS feeds).

CSV

CSV (Comma-Separated Values) is a simple tabular format where each line is a record and each column a field, separated by a comma (or semicolon). It opens directly in Excel, Numbers, Google Sheets or LibreOffice, making it ideal for bulk-editing data.

Round-trip

Round-trip is the ability to convert an XML file into editable CSV, then rebuild the original XML exactly from the edited CSV. Unlike a one-way converter, it preserves the exact structure (field order, namespaces, nesting) so the file can be re-imported without errors.

Tag / Element

A tag is the marker that delimits a piece of data in XML: an opening tag <title> and a closing tag </title>. The opening tag, content and closing tag together form an element. Elements can contain other elements, creating a hierarchy.

Attribute

An attribute is a key-value pair placed inside an element's opening tag, e.g. <price currency="EUR">19</price>. It carries metadata about the element. In a spreadsheet, an attribute becomes its own column (often noted with a prefix such as @currency).

Namespace

A namespace prevents tag-name collisions by prefixing elements, e.g. g:title in a Google Shopping feed or xi:include. It is declared with an xmlns attribute. A good conversion tool must preserve namespaces so the file stays valid.

CDATA

A CDATA block (<![CDATA[ ... ]]>) lets you include raw text containing reserved characters (<, >, &) without escaping them — typically HTML inside a product description. The content is treated as plain text, not markup.

XML entity

An entity is a shortcut representing a reserved or special character: &lt; for <, &amp; for &, &#233; for é. It keeps the file well-formed. Custom entity declarations (<!ENTITY>) are blocked by safe tools because they can be used for attacks (XXE).

Encoding (UTF-8, UTF-16…)

Encoding defines how characters are represented as bytes. UTF-8 is the universal standard; you also encounter UTF-16 (Salesforce Commerce Cloud exports) or ISO-8859-1. A wrong encoding produces garbled characters ("é" instead of "é"). A good tool auto-detects the encoding.

XSD / DTD (schema)

An XSD (XML Schema Definition) or DTD (Document Type Definition) describes the expected structure of an XML file: which elements, in what order, with which types. It is used to validate that a file conforms before importing it into a system.

Product feed

A product feed is an XML file (often extended RSS) listing a product catalog for a platform: Google Shopping, Meta/Facebook, price comparison engines. Each product is an <item> element with fields such as title, price, availability and id.

XML sitemap

An XML sitemap lists a site's URLs to help search engines discover them, with optional metadata (last-modified date, priority, change frequency). It follows a strict format and is submitted to Google Search Console.

Prolog / XML declaration

The prolog is the start of an XML file, before the root element. It contains the <?xml version="1.0" encoding="UTF-8"?> declaration and, optionally, a DTD. It is the only place a DOCTYPE declaration is valid — which is why attack vectors should only be scanned there.

XXE (XML External Entity)

The XXE attack abuses external entities in a malicious XML to read server files or make unauthorized requests. A safe conversion tool blocks DOCTYPE and ENTITY declarations, as well as external SYSTEM/PUBLIC references.