Use paths

A path is a named, highlighted route through a process flow — the happy path, an exception route, a scenario you want to walk an audience through.

Prerequisites

Viewing and stepping paths works on any diagram you can read; creating and editing paths requires the diagram checked out to you.

Open the Paths panel in the side toolbar and select Add Path.
Click the path's waypoints in order — shapes, and connector lines where the route is ambiguous. A filled circle in the path's color marks each shape you picked, and the route between the waypoints is drawn in the same color. The segments the editor works out for itself are drawn thinner and lighter. Click a waypoint again to remove it. The path follows the shortest connected route between its waypoints. At a branch with no waypoint, it takes the shorter side. Add a waypoint on the branch you want.
Name the path (paths auto-name "Path 1", "Path 2", … until you rename) and pick a color to tell it apart from others.

Edit or remove a path from the same panel (Edit Path, Remove Path). If a path's start or end shape is deleted, the panel flags it.

Select a path in the panel to highlight it on the canvas: its shapes take a thicker outline in the path's color, and the rest of the diagram washes out. A shape that two or more selected paths share takes a black outline.
Previous Step / Next Step walk the route shape by shape, and the Paths Navigator keeps your place.
Select several paths at once with Shift-click (a range) or Ctrl-click (individual paths).

Right-click a shape or connector while the path is selected and choose Share Link to Path — for the recipient, the link opens the diagram with the Paths panel open and the path selected and highlighted.
The path's narrative — the diagram's default narrative restricted to the path's shapes — is available from the panel for viewing and download.
Exporting the diagram to an image (SVG, PNG, JPG) while paths are selected exports them highlighted.