Screen resolution and monitor size are related, but not universal. Resolution refers to the number of pixels a screen can display within a given area. Screen resolution is usually expressed in pixels per linear inch of screen. Most personal computer displays have resolutions that vary from 72 to 96 pixels per inch (ppi). The resolution of the display screen is dependent on how the monitor and display card are configured, but it's safe to assume that most users fall into the lower end of the range, or about 72 to 80 ppi.
Screen resolution refers to the sizes of the display. At a higher resolution the items on the screen will actually be smaller, but there will be more room on the screen. The current trend is that more and more computers are using a screen size of 1024x768 pixels or more:
| 2007 | Higher | 1024x768 | 800x600 | 640x480 | Unknown |
| January | 26% | 54% | 14% | 0% | 6% |
| 2006 | |||||
| July | 19% | 58% | 17% | 0% | 6% |
| January | 17% | 57% | 20% | 0% | 6% |
| 2005 | |||||
| July | 14% | 55% | 25% | 0% | 6% |
| January | 12% | 53% | 30% | 0% | 5% |
| 2004 | |||||
| July | 10% | 50% | 35% | 1% | 4% |
| January | 10% | 47% | 37% | 1% | 5% |
| 2003 | |||||
| July | 8% | 43% | 44% | 2% | 5% |
| January | 6% | 40% | 47% | 2% | 5% |
| 2002 | |||||
| October | 6% | 38% | 49% | 2% | 5% |
Many users are using 800x600 display screens because:
Images that will be printed require high resolution, where images on the screen can be much lower. Since most monitors can only display up to 96 px resolution, anything higher than that in not necessary and will create long download times for the viewer. Do not confuse picture size with resolution. If you have a picture on your site that takes up half your screen and you have a professional printer grab it for a magazine article, it will print out about the size of a postage stamp.
You never really know what the viewer is using for a display. I personally have a wide screen monitor and run my browser at full screen. Some people have a large monitor and run the browser window in a smaller size. So even if you know which monitor everyone is using and which resolution they are using, you still don't know how big the viewer's browser window is.
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