all by use

Use your mac as a keyboard for iOS and android devices.

Use one mouse/keyboard to control several Macs.

Use a Mac computer as a video surveillance camera.

Use a screensaver as your desktop wallpaper.

Use Quartz Compositions, videos, or Web pages as wallpaper.

Use QuickTime movies as screen savers.

Use your digital camcorder to backup data.

Use your volume keys to adjust the volume in iTunes, via AirPlay.

Use a single iSight or other webcam with multiple applications.

Use Flash to build desktop apps.