For normal text (not markup), there are no special characters: just make sure your document refers to the correct encoding scheme for the language and/or writing system you want to use, and that your computer correctly stores the file using that encoding scheme. See for a longer explanation.

If your keyboard will not allow you to type the characters you want, or if you want to use characters outside the limits of the encoding scheme you have chosen, you can use a symbolic notation called ‘entity referencing’. Entity references can either be numeric, using the decimal or hexadecimal code point for the character (eg if your keyboard has no Euro symbol (€) you can type &#8364;); or they can be character, using an established name which you declare in your DTD (eg <!ENTITY euro "&#8364;">) and then use as &euro; in your document. If you are using a Schema, you must use the numeric form for all except the five below because Schemas have no way to make character entity declarations.

If you use XML with no DTD, then these five character entities are assumed to be predeclared, and you can use them without declaring them:

&lt;

The less-than character (<) starts element markup (the first character of a start-tag or an end-tag).

&amp;

The ampersand character (&) starts entity markup (the first character of a character entity reference).

&gt;

The greater-than character (>) ends a start-tag or an end-tag.

&quot;

The double-quote character (") can be symbolised with this character entity reference when you need to embed a double-quote inside a string which is already double-quoted.

&apos;

The apostrophe or single-quote character (') can be symbolised with this character entity reference when you need to embed a single-quote or apostrophe inside a string which is already single-quoted.

If you are using a DTD then you must declare all the character entities you need to use (if any), including any of the five above that you plan on using (they cease to be predeclared if you use a DTD). If you are using a Schema, you must use the numeric form for all except the five above because Schemas have no way to make character entity declarations.

There are no reserved words as such in the user namespace of XML: you can call an element element and an attribute attribute and so on as in the following (ludicrous) example:

     
     
     
     ]>
       
      
       bar
      
     

where the file SYSTEM contains the declaration: <!ELEMENT ELEMENT (#PCDATA)> and the file ENTITY does not even exist.

There are keywords like DOCTYPE and IMPLIED which are reserved Names, but they are prefixed by a flag character (the Markup Declaration Open character or the Reserved Name Indicator) so that they cannot be confused with user-specified Names.

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