Some text editors are small and simple, while others offer broad and complex functions. For example, Unix and Unix-like operating systems have the pico editor (or a variant), but many also include the vi and Emacs editors. Microsoft Windows systems come with the simple Notepad, though many people—especially programmers—prefer other editors with more features. Under Apple Macintosh's classic Mac OS there was the native SimpleText, which was replaced in Mac OS X by TextEdit, which combines features of a text editor with those typical of a word processor such as rulers, margins and multiple font selection.
These features are not available simultaneously, but must be switched by user command, or through the program automatically determining the file type.
Most word processors can read and write files in plain text format, allowing them to open files saved from text editors.Saving these files from a word processor, however, requires ensuring the file is written in plain text format, and that any text encoding or BOM settings won't obscure the file for its intended use. Non-WYSIWYG word processors, such as WordStar, are more easily pressed into service as text editors, and in fact were commonly used as such during the 1980s.
The default file format of these word processors often resembles a markup language, with the basic format being plain text and visual formatting achieved using non-printing control characters or escape sequences. Later word processors like Microsoft Word store their files in a binary format and are almost never used to edit plain text files.