GUI: OS X 10.11 El Capitan

Released in 2015, El Capitan was primarily a refinement of the changes released in Yosemite. Though it didn't include a lot of notable new features, it was considerably more stable than its predecessor.

Installation:

El Capitan was the first version to use a boot screen style visual for the installation and update process.

Empty Desktop:

Desktop with Applications:

TextEdit:

Calculator:

Calendar:

Contacts:

Media Player (QuickTime X):

Media Player (iTunes 12):

Volume:

Browser (Safari 9):

Mail:

System Preferences:

Appearance:

Desktop:

Screensaver:

Display:

Keyboard:

Mouse:

Date and Time:

International:

Accessibility:

Power Management:

Application Manager (Dock):

File Manager:

Activity Monitor:

Help:

Search:

Trash:

Terminal:

Boot Screen:

Login Screen:

Logout Prompt:

Shutdown Prompt:

Restart Prompt:

Shutdown:

About This Mac:

About Application:

Font Selection:

Open File:

Color Selector: