The following is an alphabetical list of terms you’ll encounter throughout this manual, some of which may be unfamiliar or have special uses particular to OmniFocus.

An item that’s part of a project, or part of a group within a project.
The status for an item that’s planned for completion, or a context that’s currently in use.
A database of jettisoned items that you’ve decided aren’t relevant to your current plans by virtue of their age and dropped or completed status. Using an archive helps keep your main database easy to sync and search, while providing a historical document that’s easy to access for reference when necessary.
A view setting that displays items that aren’t blocked, deferred, or on hold.
A copy of your database automatically generated by OmniFocus and stored for safekeeping should something go amiss with your main database. Backups are automatically created every two hours while OmniFocus is open, and up to 100 are kept before the oldest is discarded.
The status of an action in a sequential project that is ordered to come after the first available action.
Clean Up
A clerical process that tidies the views on your database when you switch between them, or when it’s triggered with a menu item or toolbar button. Usually this involves hiding completed items or moving actions into their proper places; you can fine-tune how clean up works in Preferences ▸ Organization.
The status assigned to an item when you’ve finished it, or finished all the actions that comprise it (in the case of a project or group).
The person, place, thing, state of mind, or other factor most relevant to the completion of a given action or project. These exist outside the project hierarchy and represent another axis from which to view the items you’ve accumulated in your database.
Defer Date
A date and time assigned to an item that you don’t want to (or can’t) consider for completion until later. When the defer date is reached, the item becomes available for further execution.
Due Date
A date and time assigned to an item by which the item must be completed.
Due Soon
A status for items whose due dates are approaching. Items that are due soon are styled in amber for greater visibility. The exact meaning of Due Soon is configurable in OmniFocus ▸ Preferences ▸ Dates & Times.
First Available
A view setting that affects how actions in projects are displayed. A sequential project has one available action and one first available action. A parallel project has one first available action and many available actions. A single action list potentially has many “first available” actions.
A mark of privileged, eye-catching status bestowed on an item. What this special status denotes is completely up to you, but it’s a great way to keep important things from falling through the cracks. Items that are flagged are styled in orange for greater visibility.
A feature of OmniFocus Pro that applies to projects and folders (focusing on an action brings the project that contains it into focus). When focused, OmniFocus excludes all items in your database from view other than those in the projects or folders you have selected. Browsing between perspectives retains focus on these items, so you can attack them from multiple angles without distraction.
Focus Bar
A horizontal bar that appears beneath the toolbar to denote that you’re focused (in OmniFocus Pro) or viewing a database other than your current primary one (such as a backup, an archive, or someone else’s database they sent you to take a look at).
A collection items nested hierarchically within another item. Groups created from inbox items are item groups, while groups created within projects are action groups (also sometimes called sub-projects).
Items that live in your database but aren’t exposed by the View options of your current perspective are considered hidden. OmniFocus lets you know if you’re about to delete hidden items accidentally; see the Cleaning Up section for details.
The built-in perspective designed to hold tasks and to-dos that you’ve entered into OmniFocus as items, prior to processing them into projects, actions, and groups. Once an item becomes a project or an action it’s moved out of the inbox at the next clean up.
The pane on the right side of the OmniFocus window that provides editable details about your current selection in the sidebar or the main outline.
Items are representations of tasks and to-dos in an OmniFocus database. Types of items include: Inbox Items, Actions, Projects, and Groups.
Main Outline
The central portion of an OmniFocus window, where a hierarchical view of your database is (usually) displayed. Specific perspectives (such as Contexts and Forecast) have specialized ways of displaying your data that eschew or modify the typical project hierarchy.
OmniFocus Window
A viewport onto an OmniFocus database, including several subsections: the main outline, sidebar, inspector, toolbar, bottom bar, and (occasionally) the focus bar.
On Hold
A status for projects and contexts that aren’t relevant to your plans right now, but may be in the foreseeable future.
A status for items whose due dates are past. Items that are overdue are styled in red for greater visibility.
A project or group that doesn’t place particular emphasis on the order in which its actions are completed. All actions are considered available, though the topmost action is still considered the first available action for the purposes of view settings.
An item with its defer date set for some time in the future. Pending is a synonym for deferred; this particular term is only found in OmniFocus Pro as a filtering option for projects in custom perspectives that use the project hierarchy.
A view on your OmniFocus database, displayed in an OmniFocus window. OmniFocus 2 comes with six built-in perspectives and two transient reference perspectives (Completed and Changed), and custom perspectives can be added in OmniFocus Pro.
Perspective Tabs
The vertical column of tabs on the leftmost side of an OmniFocus window, displaying a list of persistent perspectives for your browsing pleasure. The six built-in perspectives are included here by default (perspective tabs can be hidden, revealed, and rearranged in OmniFocus Pro).
Perspectives Window
A window in OmniFocus Pro that’s split into two parts: the perspectives list (where perspectives are added, renamed, reordered, and have their tab visibility set) and the perspectives editor (where perspectives are created and customized).
A to-do item that’s larger in scope or permanence than a simple action, potentially containing several actions and groups within it that must be completed before the project can be marked complete.
A view setting that displays all items that haven’t been completed or dropped.
A project or group whose actions must be completed in a specific order. The first action in the list is the only one available for completion.
The vertical space to the left of the main outline that’s displayed by default along with all perspectives but the Inbox. It contains the project hierarchy in perspectives that use it; otherwise it shows the context list or a special customized view (as with Forecast).
Single Action List
A project whose actions are unrelated to a sequence of any sort, or one that’s maintenance-oriented as opposed to completion-oriented. All actions in a single action list are considered equally available.
A project with no remaining actions (all of its actions have been completed). This status is used primarily as a filter for custom perspectives in OmniFocus Pro.
A term synonymous with action group; a group of actions nested hierarchically within a project.
Status Circle
A graphical display of an item’s status (due soon, overdue, flagged, or repeating), as well as a target to click to mark an item completed (hooray!) or to flag it.
In the context of this manual, a task is something you’d like to accomplish in the real world that you’d capture with OmniFocus (where it would then become an item). To-do is another word with the same meaning.