Finder sidebar
Finder windows have a sidebar with items you frequently use, including folders, disks, and tags.
By default, the sidebar is divided into four sections.
Favorites
Includes items you use most frequently, such as AirDrop, recently used files, the Applications folder, your Documents folder, and the Downloads folder. You can add other folders by dragging them into the Favorites section.
iCloud
Includes items automatically stored in iCloud Drive, items you’re sharing and that are shared with you and, when you turn on iCloud Desktop & Documents Folders, the Desktop and Documents folders in iCloud.
Locations
Displays icons that represent your computer’s disks, any disks or devices attached to your Mac, and any available optical drives.
Shared computers and servers on your local network are also listed here, including AirPort devices and Time Capsules.
Tags
Tags provide quick access to all the items using a particular tag. Click a tag to see files using that tag.
At any time, you can customize the Finder sidebar. In the Finder, choose Finder > Preferences, then click Sidebar or Tags.
To increase the size of icons and text in the Finder sidebar, choose Apple menu 
, then choose a size from the “Sidebar icon size” pop-up menu.