Editing Outliner (section)

{{Short description|Type of software to organize texts}}
[[File:Org-mode-show-all.png|thumb|350px|An outline in [[Emacs]] [[Org-mode]].]]
An '''outliner''' (or '''outline processor''') is a specialized type of [[text editor]] ([[word processor]]) used to create and edit [[Outline (list)|outline]]s, which are [[text file]]s which have a [[tree structure]] or a [[tree view]], for organization. Textual information is contained in discrete sections called "nodes", which are arranged according to their topic–subtopic (parent–child) relationships, like the members of a [[family tree]]. When loaded into an outliner, an outline may be [[text folding|collapsed or expanded]] to display as few or as many levels as desired.

Outliners are used for storing and retrieving textual information, with terms, phrases, sentences, or paragraphs attached to a tree.  So rather than being arranged by document, information is arranged by topic or content. An outline in an outliner may contain as many topics as desired.  This eliminates the need to have separate documents, as outlines easily include other outlines just by adding to the tree.

The main difference between a hand-written outline and a digital one is that the former is usually limited to a summary or blueprint of a planned document, while the latter may easily include all of the content of the entire document and many more.  In other words, as a hand-written work an outline is a writing tool, but on a computer, it is a general purpose format supported by a robust development and display medium capable of handling knowledge from its creation to its end usage.

Outliners may be used in [[content creation]] instead of general word processors for capturing, organizing, editing, and displaying knowledge or general textual information. Outliners are ideal for managing lists, organizing facts and ideas, and for [[Abstract syntax tree|writing computer programs]].  They are also used for goal and task management (including [[personal information management]] and [[project management]]), and for writing books and movie scripts.

An alternative to outliners are [[mind mapper]]s, which display a tree structure as a [[Tree structure#Classical node-link diagrams|node–link diagram]].