Pro Tools 101_ An Introduction to Pro Tools 11 ( PDFDrive )

In Shuffle mode, clip movement is constrained by other clips, and any
changes you make affect the placement of subsequent clips on the track. When
you move a clip in Shuffle mode, it will snap to the previous or next clip on
the track. Additionally, when you perform an edit (trim, cut/delete, or paste
material), all clips to the right will slide along the Timeline in train-car
fashion to make space (when adding material) or to close a gap (when
removing material).
Use Shuffle mode as a convenient way to make clips line up next to each
other, without overlapping or leaving silence between them.
Slip Mode
In Slip mode, you can move, trim, cut, or paste clips freely within a track
without affecting the placement of other clips on the track. In this mode, you
can place a clip anywhere on a track, leaving space between it and other
clips, if desired. It is also possible to move a clip so that it overlaps or
completely covers another clip.
Use Slip mode when you want the Trim, Selector, Grabber, and Pencil tools
to work without restrictions to placement in time.
Spot Mode
In Spot mode, you can move or place clips at precise locations by specifying
the destination location in a dialog box. As in Slip mode, edit operations do
not affect the placement of other clips on the track.
When Spot mode is enabled, Pro Tools prompts you with a dialog box when
working with clips, allowing you to specify the start, end, duration, or other
relevant parameters. Use Spot mode when you want to control the placement
or duration of a clip using precise numerical values.
Grid Mode
In Grid mode, clips and MIDI notes that are moved, trimmed, or inserted will
snap to the nearest time increment using the currently selected Time Scale
and Grid size. Grid mode can be applied using either Absolute or Relative
positioning options. (See Lesson 8 for details.)
Use Grid mode for making precise edits and aligning clips and selections
using precise time intervals.