The XQuery language uses a number of keywords and symbols in its expressions. All of the keywords are case-sensitive, and they are generally lowercase. In some cases, a symbol (such as *) or keyword (such as in) has several meanings, depending on the context. The XQuery grammar is defined in such a way that these multiuse operators are never ambiguous.

Names are used in XQuery to identify elements, attributes, types, variables, and functions. These names must conform to the rules for XML qualified names, meaning that they can start with a letter or underscore and contain letters, digits, underscores, dashes, and periods. Like the keywords, they are also case-sensitive. Because there are no reserved words in the XQuery language, a name (for example, a variable or function name) used in a query may be the same as any of the keywords, without any ambiguity arising.

All names used in XQuery are namespace-qualified names. This means that they can be prefixed in order to associate them with a namespace name, and that they may be affected by default namespace declarations.