Entity references are used as substitutions for specific characters (or any string substitution) in XML. A common use for entity references is to denote document symbols that might otherwise be mistaken for markup by an XML processor. XML predefines five entity references for you, which are substitutions for basic markup symbols. However, you can define as many entity references as you like in your own DTD. (See the next section.)
Entity references always begin with an ampersand (&) and end with a semicolon (;). They cannot appear inside a CDATA section but can be used anywhere else. Predefined entities in XML are shown in the following table: