Character entity references, or entities for short, provide a method of entering characters that cannot be expressed in the document's character encoding or that cannot easily be entered on a keyboard. Entities are case-sensitive and take the form &name;. Examples of entities include © for the copyright symbol and Α for the Greek capital letter alpha.
In addition to entities, authors can use numeric character references. While entities are limited to a subset of Unicode characters, numeric character references can specify any character. Numeric character references may be given in decimal or hexadecimal, though browser support is stronger for decimal references. Decimal references are of the form &#number; while hexadecimal references take the case-insensitive form &#xnumber;. Examples of numeric character references include © or © for the copyright symbol, Α or Α for the Greek capital letter alpha, and ا or ا for the Arabic letter ALEF.
Note that hexadecimal character references will cause errors with current validators since these references are defined in a recent revision to the SGML standard that is not yet supported by validators.
The following documents feature tables of the character entity references in HTML 4.0, along with the numeric character reference in decimal and hexadecimal. A rendering of each character reference is provided so that users may check their browsers' compliance.