The Edit menu groups together the actions related to the edition, and so will be mostly used while in Editor mode.

Undo (action)Reverts the last editing operation, namely action
RedoDoes the last editing operation again, after an Undo
Undo Selection ChangeReverts the last selection operation
Redo Selection ChangeDoes the last selection operation again after an Undo Selection Change
CutDeletes the current selection, but puts it in memory ready to be pasted
CopyCopies the current selection to memory
PastePastes the memory at the edit point, after a Cut or Copy operation
Select
Select All ObjectsSelects all the regions and automation points in the session
Select All TracksSelects all the tracks, busses and control masters in the session
Select All Visible LanesSelects all the visible tracks, busses and control masters, i.e. those marked v in the Editor List
Deselect AllDeselects all objects or tracks, nothing is selected
Invert SelectionSelect the previously unselected regions, and deselect the previously selected ones
Set Range to Loop RangeCreates a range selection on the selected tracks, based on the selected loop markers, and switches to Range Mode tool
Set Range to Punch RangeSame as above, based on the selected punch markers
Set Range to Selected RegionsSame as above, based on the selected regions (i.e. from the start of the earliest region to the end of the latest one)
Select All After Edit PointSelect all the regions and automation points that exist after the Edit Point, even if the region starts before it. If some tracks are selected, only selects on these tracks.
Select All Before Edit PointSame as above, but before the Edit point (i.e. to the left of it)
Select All Overlapping Edit RangeSelect all the regions and automation points of which at least a part is in the current selection range
Select All Inside Edit RangeSelects all the regions that are completely inside the selection range, i.e. their start and end are inside the range. If some tracks are selected, only selects on these tracks.
Select All in Punch RangeSelects all the regions of which a part in in the punch range. If some tracks are selected, only selects on these tracks.
Select All in Loop RangeSame as above, based on the loop range
Move Range Start to Previous Region BoundaryExtends the left boundary of the range to the left to the next region start or end. The region must be in the range.
Move Range Start to Next Region BoundarySame as above, to the right (reduces the selection)
Move Range End to Previous Region BoundarySame as above, with the right edge of the range, to the left (reduces the selection)
Move Range End to Next Region BoundarySame as above, with the right edge, to the right (extends the selection)
Start RangeSets the left edge of the range to the Edit point
Finish RangeSets the right edge of the range to the Edit point
Select Next Track or BusSelect the track or bus under the currently selected one. If multiple tracks are selected, only the first one is considered
Select Previous Track or BusSame as above, with the track/bus above the first one selected.
DeleteDeletes all that is currently selected
CropCuts the parts of the regions that are outside the range boundaries. Only applies on the regions that belong at least in part to the range.
Split/SeparateCuts the selected regions at the Edit point, separating them in two regions
Separate
Separate UnderRemoves all the parts of the regions that are under the selected one. Once done, the selected region is alone on its part of the track.
Separate Using Loop RangeCuts the selected regions or the regions on the selected tracks along the Loop range's start and end markers. If nothing is selected, acts on all tracks at once.
Separate Using Punch RangeSame as above, with the Punch range markers
Align
Align StartMoves the selected regions to align the beginning of the regions to the Edit point
Align Start RelativeWhen multiple regions are selected, moves all the regions together as a block to align the beginning of the earliest one to the Edit point.
Align EndMoves the selected regions to align the end of the regions to the Edit point
Align End RelativeWhen multiple regions are selected, moves all the regions together as a block to align the end of the latest one to the Edit point.
Align SyncMoves the selected regions to align the Sync point of the regions to the Edit point
Align Sync RelativeWhen multiple regions are selected, moves all the regions together as a block to align the earliest Sync point to the Edit point.
Fade
Fade Range SelectionFor all the regions that either begin or end in the range, create a fade in or out on the regions length.
Set Fade In LengthIf the edit point is withing the region boundaries, adjusts selected audio regions' fade in to end at the edit point.
□ Fade InToggles the fade in on the selected region on or off
Set Fade Out LengthSame as above, for the fade out
□ Fade OutToggles the fade out on the selected region on or off
Tag Last CapturePrompts for a text to tag the last record, this tag is visible in the Region list
Remove Last CaptureDestroy the last recording. A prompt reminds the user this cannot be undone.
Edit point
Change Edit PointToggles between the mouse and the playhead as the Edit point
Change Edit Point Including MarkerToggles between the mouse, the playhead and marker as the Edit point
Toggle SnapActivates/deactivates snapping, which aligns region boundaries to the closest selected time marker when moved
Snap & Grid
Previous Quantize Grid ChoiceChanges the snap quantization to the previous one in the list below
Next Quantize Grid ChoiceChanges the snap quantization to the next one in the list below
○ No GridDisables snapping, i.e. allows free movement of regions and boundaries
○ BarSnaps to the next musical bar, bars can be set and seen in the Ruler
○ 1/4 Note → 1/28 (32nd septuplet)Selects the division of musical time to snap to
Tempo
Set Tempo from Region = BarComputes the tempo so that the duration of the first selected region is 1 bar. Ardour prompts if the user wants it to be the global tempo, or a tempo marker at the beginning of the region used
Set Tempo from Edit Range = BarSame thing, with the current Range instead of a region
□ Smart ModeToggles the Smart Mode, allowing the mouse to be in Range Mode in the upper half of a region, and in Grab Mode in the lower half
□ Show Automation Lane on TouchWhen toggled on, clicking on a plugin parameter, hardware controller, etc… makes Ardour show the relevant automation lane
Lua Scripts
□ Script ManagerShows the Script manager, allowing to use and manage the Lua scripts in the session
Action script #nExecutes the nth script. The script list is defined in the Script Manager.
PreferencesDisplays the Preferences panels, allowing to change Ardour's behaviour