Because of the Apple PC’s excellent screen, the presentation of color gradation, hue, and contrast is much better than that of traditional PC computers. Thus it is the main choice for many professional video and photograph editors. In particular, the recent launch of the Apple MacBook Pro and MacBook Mini with retina screens further established that Apple has the professional user in mind. The only drawback is that MacBook Pro’s 13 or 15.4-inch screen is too small. In fact the MacBook Air only has an 11.6-inch screen. If you usually use your Mac only to browse the web, screen size it is not so important. But for those who run complex software (such as Xcode or Photoshop), the MacBook’s screen cannot cope with all the windows. Users will need to keep pressing Option-Tab to switch between windows. An external monitor does allow you to have more display space, and helps you get the job done more efficiently.
It is worth mentioning that not only does an external monitor offer a larger display space, but there is also some software optimized for multi-display software (such as Aperture and iMovie) that offers more convenience. For example, if you use iMovie to edit video on a single display, the movie preview windows will be pushed to the upper-right corner of the screen by other windows. If you have two monitors, you can use one screen exclusively for the movie preview and put the other windows on the second monitor.