Paths
provide smooth outlines that you can convert into precise selection borders.
You also can convert selection borders into paths, using the Direct Selection
tool for
fine-tuning.
You can define any closed path as a selection border. A closed path can be added to, subtracted from, or combined with the current selection.
Click the Load Path as a Selection button at
the bottom of the Paths palette.
Ctrl‑click (Windows) or Command-click (Mac OS) the path thumbnail in the Paths palette.