Plain text

In computing, plain text refers to the formatting (or general lack thereof) of textual material, usually in a disk file. Thus, "I'm keeping that letter in plain text form until someone insists on getting it in the Foo format".

The related term, plaintext, is most commonly used in a cryptographic context, while cleartext usually refers to lack of protection from eavesdropping. Usage of these terms is such that there is some confusion amongst them, especially among those new to computers, cryptography, or data communications.

Plain text (in contradistinction to formatted text) is also used to refer to files in ASCII text or other human-readable form (ie, when using a simple editor). This usually excludes files stored with formatting embedded in the file, such as Microsoft Word '.doc' files, or WordPerfect '.doc' files. Note that the embedded formatting is different in these two, homonymic, file types, though each program can translate between formats from the other (while reading or saving files). They can also, with some care in the importing and exporting, edit plain text files.

Plain text files include, somewhat circularly, any file that can be opened, read, and edited with a text editor which handles such files. Examples include Notepad (on Microsoft Windows), edlin (on Microsoft DOS), ed/vi/EMACS (on Unix, Linux, and elsewhere), pico, nano, SimpleText (on Mac OS), or TextEdit (on Mac OS X). In the Windows world, 'Text' and 'Text with Line Breaks' are the same thing save for the inclusion of characters meaning 'end of line' in the latter. 'MS-DOS text' allows inclusion of a few additional characters conforming to DOS usage.

Most programming languages compilers require programs written for them (ie, their source code files) to be in plain text form, as do HTML, XML, LaTeX, TeX, PostScript, etc.