QUICK LOOK Finder’s sidebar
By default, the sidebar appears at the left-hand side of all Finder windows, providing fast singleclick access to folders, mounted media, shared computers and tags.
Items stashed in the sidebar are grouped into categories: Favorites, Devices, Shared and Tags, to help make it easier to find what you’re looking for.
You can store custom items under Favorites. Folders and searches are the best things to place there. Add documents and apps if you like, but avoid too much clutter.
In Preferences you can adjust what’s shown in the Finder sidebar. Individual folder preferences and view options can also be amended to suit.