Org-mode (also: Org mode; pronounced /ɔːɡ məʊd/) is an editing and organizing mode for notes, planning, and authoring in the free software text editor Emacs. The name is used to encompass plain text files ("org files") that include simple marks to indicate levels of a hierarchy (which could be the outline of an essay, a topic list with subtopics, nested computer code, ...), and an editor with functions that can read the markup and manipulate hierarchy elements (expand/hide elements, move blocks of elements, check off to-do list items, ...).