Org-mode is a document editing, formatting, and organizing mode, designed for notes, planning, and authoring within the free softwaretext editorEmacs. The name is used to encompass plain text files that include simple marks to indicate levels of a hierarchy, and an editor with functions that can read the markup and manipulate hierarchy elements. Org-mode was created by Carsten Dominik in 2003, originally to organize his own life and work, and since the first release numerous other users and developers have contributed to this free software package. Emacs includes Org-mode as a major modeby default. Bastien Guerry is the current maintainer, in cooperation with an active development community. Since its success in Emacs, some other systems have also begun providing functions to work with org files. Almost orthogonally, Org-mode has functionalities aimed at executing code in various external languages; these functionalities form org-babel.
System
The Org-mode home page explains that "at its core, Org-mode is a simple outliner for note-takingand list management" The Org system author Carsten Dominik explains that "Org-mode does outlining, note-taking, hyperlinks, spreadsheets, TODO lists, project planning, GTD, HTML and LaTeX authoring, all with plain text files in Emacs." The Org system is based on plain text files with a simple markup, which makes the files very portable. The Linux Information Project explains that "Plain text is supported by nearly every application program on every operating system". The system includes a lightweight markup language for plain text files, allowing lines or sections of plain text to be hierarchically divided, tagged, linked, and so on.
Functionality
This section gives some sample uses for the hierarchical display and editing of plain text.
To-do lists often have subtasks, and so lend themselves to a hierarchical system. Org-mode facilitates this by allowing items to be subdivided into simple steps, and given tags and properties such as priorities and deadlines. An agenda for the items to be done this week or day can then be automatically generated from date tags.
Extensive linking features, to web pages, within the same file, to other files, to emails, and also allows defining custom links
An org-mode document can also be exported to various formats, these formats being used to render the structural outline in an appropriate fashion. It can also use formatting markup , with facilities similar to those present in Markdown or LaTeX, thus offering an alternative to these tools.
Org-babel
Org-mode offers the ability to insert source code in the document being edited, which is automatically exported and/or executed when exporting the document ; the result produced by this code can be automatically fetched back in the resulting output. This source code can be structured as reusable snippets, inserted in the source document at the place needed for logical exposition thus allowing this exposition to be independent of the structure needed by the compiler/interpreter. Together with the markup facilities of org-mode, these two functionalities allow for
Literate programming, by decoupling the exposition of the functions of a program from its code structure, and
Reproducible research, by the creation of a consistent document consolidating exposition, original data, analyses, discussion and conclusion, in a way that can be reproduced by any reader using the same software tools.
As of November 2018, org-babel directly supports more than 50 programming languages or programmable facilities, more than 20 other tools being usable via contributed packages or drivers.
Integration
Org-mode has some features to export to other formats, and other systems have some features to handle org-mode formats. Further, a full-featured text editor may have functions to handle wikis, personal contacts, email, calendars, and so on; because org-mode is simply plain text, these features could be integrated into org-mode documents as well. From org-mode, add-on packages export to other markup format such as MediaWiki, to flashcard learning systems implementing SuperMemo's algorithms. Outside of org-mode editors, org markup is supported by the GitLab and GitHub code repositories, the JIRAissue tracker, Pandoc, and others.
