This online free HTML Entity Decoder/Encoder converts all applicable characters to their corresponding HTML entities in other words This utility encodes or decodes HTML entities in the supplied text. From time to time webmasters want to encode their text so that certain specials characters are preserved regardless of a user’s character set. Certain characters have special significance in HTML and should be converted to their correct HTML entities to preserve their meanings.For example, it is not possible to use the < character as it is used in the HTML syntax to create and close tags. It must be converted to its corresponding &lt ; HTML entity to be displayed in the content of an HTML page.this tool will change all special characters while preserving any HTML tags it is used to represent reserved characters within HTML documents that are not intended to be part of the HTML structure. Usage is very simple; To encode a regular text to HTML Entities, type in the box and click the Encode button , To decode HTML Entities to regular text, type in the box and click the Decode button.
for more information: Wikipedia – List of XML and HTML character entity references