What Is Screen Resolution? - CSS Tutorials - Page Layout and Background Image Design

Screen resolution is measure by how many graphical points (pixels) per inch or DPI (dots per inch) on a computer system. Screen resolution can be changed within a range on most of today's computer systems.

For example, on a Windows system, you can go to the Control Panel, run Display, and go to the Settings tab to change the number of graphical points on screen in the range of 800x600 and 1400x1050 pixels.

To calculate the screen resolution, you should divide the number of points on the screen by the screen size in inches. For example, if you set 800x600 pixels on a screen of 11.5x8.5 inches, your screen resolution is about 70DPI.

If you set 1024x768 pixels on a screen of 11.5x8.5 inches, your screen resolution is about 90DPI.

Screen resolution must be considered when you design your Web page, because your page size will be affected by the screen resolution of your visitor's computer system. Generally, your page will look smaller on computer systems with higher resolutions.