The Finder sidebar allows you to navigate through your folders, drives, files, apps, and shared items on your Mac. Furthermore, there are many ways one could customize the sidebar and make it better. Here are a couple of quick tips to get started.
You can add new items and locations to the Favorites, Shared, or Devices sections of the sidebar. Click on the Finder menu> Preferences > Sidebar tab. Tick the checkboxes next to the items you want to be displayed in the sidebar.
How To Add Your Favorite Apps to the Sidebar
Mac OS X gives you the ability to pin your favorite apps to the sidebar. Hold down the Command key and then drag the desired app shortcut to the Favorites section of the sidebar.
How To Change the Size of the Sidebar Icons
Click on the Apple menu > System Preferences > General. Click on the Sidebar icon size drop-down menu and select the desired preset: Large, Medium, or Small.