In cryptology this is the commonly used phrase to refer to a message that is not encrypted (encoded). The unencrypted message that an encrypted message, or ciphertext, is created from.

Could also be written as plain text.

(HTML tag) <PLAINTEXT>

'The Unstoppable Monster'. This HTML tag has for effect to escape all remaining tags until the end of the document. There exists no </PLAINTEXT> tag so it is irreversible. From this tag on, all the HTML source will be shown using the last rendering settings.

Combined with setting the font color equal to the current background color, it can be used to neuter any html directive including javascript that a nosy hosting service may append to your page.

Deprecated since HTML 2.0 but still functional in most browsers! Use <PRE> for monospaced, preformatted text.