Undooptie

Undooptie refers to the feature in software that allows a user to reverse one or more previously executed actions. It provides a safety net to correct mistakes and experiment without committing irreversible changes. In most applications the undo feature is complemented by a redo option to reapply actions that were undone.

The concept emerged from early text editors and has become a standard part of graphical user interfaces. Modern implementations rely on an action history or command pattern, recording the sequence of user actions and their inverse effects. When the user invokes undo, the system applies the inverse components of the most recent action and stores it for possible redo.

In practice, undo is usually implemented as a stack of reversible actions. Each action knows how to reverse itself, and sometimes data is stored to restore prior state. Redo uses a separate stack or can reapply actions after they have been undone. The scope of undo can be per-document, per-session, or global across an application, and the depth may be fixed or configurable by the user.

Some actions are not undoable, such as irreversible changes to external systems, certain autosaves, or operations that permanently delete data unless a confirmation is provided. Autosave, version history, and checkpointing can provide additional safety nets beyond a single-step undo.

Common examples of the undo feature include the Ctrl+Z or Cmd+Z keyboard shortcuts and corresponding menu items. Undooptie remains a central usability feature in software design, balancing quick reversal with the complexity of keeping consistent state.

See also: Redo, Version control, Auto-save, History.