Press ⇧⌘G in Finder, or in any Open or Save dialog, and a path field appears. It understands:

  • ~ for your home folder, so ~/Downloads works.
  • Absolute paths with forward slashes: /Applications, /Users/Shared, /Volumes/USB.
  • Tab to complete a folder name, like a terminal.
  • A file dragged into the field, which pastes its path.

To copy a file's path: right-click it, hold ⌥, and the menu item becomes Copy "name" as Pathname. Dragging a file into a Terminal window pastes its path as well.

The path bar (View → Show Path Bar) shows the current folder's full path at the bottom of the window; double-click any part of it to go there, or drag files onto it.