A less than sign can be ordinary text or the beginning of a tag. Entity encoding lets you represent that character in a context where it should be displayed rather than treated as markup.
HTML Entity Encoder & Decoder encodes HTML special characters or decodes recognised HTML entities. Its own output editor displays the result as plain text.
Compare one short example
Encoding <b>Ali</b> produces <b>Ali</b>. Decoding that entity string produces the literal text <b>Ali</b> in the editor, not a bold label rendered by this tool.
This distinction matters when copying the result elsewhere. An application that inserts the decoded string as HTML may interpret its tags, even though the Whatson editor did not execute them.
Ampersands and quotation marks also need attention in HTML contexts. The encoding operation handles special characters; it does not understand the complete structure of the surrounding page.
Encoding is tied to an output context
A string prepared for ordinary HTML text is not automatically safe for a JavaScript string, a URL, a CSS value or every attribute context. Use the escaping method required by the destination rather than treating one conversion as universal protection.
Decoding is not sanitising. It restores represented characters and can reveal markup that was previously written as entities. Do not assume decoded material from an unknown source is suitable for direct insertion into a website.
Repeated encoding can leave visible entity text where you expected a character. Check whether the input was already encoded before applying the operation again.
For a small repair, compare the original and converted strings side by side. If you need to remove unwanted HTML elements or establish a security policy, use a proper sanitiser designed for that purpose, not this text conversion alone.