Edit > Select > Manifold Components expands a selection to include all contiguous manifold triangles. This helps with identifying and deleting imperfect results of Points > Wrap (when Wrap Type is Volume).
A manifold triangle has three edges that each touch only one other triangle. If a manifold triangle is at a boundary, however, it has zero, one, or two edges that each touch one other triangle.
A manifold region is a set of contiguous manifold triangles.