What you should know about Display Resolutions.

A display resolution refers to the number of pixels in each dimension that can be displayed in a computer monitor, television or any other display device. Display resolution is quoted as width x height with the units in pixels. One use of this term display resolutions is in TV manufacturing. It applies to pixel array displays such as liquid crystal displays, plasma display panels, and digital light processing projectors among other similar technologies.
Display resolution is simply the number of rows and columns of pixels creating the display. The term can also be used to refer to a range of input formats that an electronic display will accept. These input formats are often greater than the screens native grid size and have to be downsized to match the screen parameters.
Factors affecting display resolution

Display Resolutions
Eye perception of display resolution can be affected by several factors including optical resolution and image resolution. Image resolution is the detail an image holds. Wallpapers with higher resolutions contain more details. Image resolution images can be tied to the overall size of the picture, physical sizes or angular subtenant. On the other hand, optical resolution is the ability of an imaging system to resolve all the details in the object that is being imaged. An imaging system can have several individual components including recording, lens and display components. Each of these components affects the optical resolution of an image. The environment in which the imaging is done can also affect the optical resolution.
Displaying more details in a small area using a higher resolution makes  wallpapers look clearer or sharper. But with the recent developments in technology it is not possible to alter the resolution because the screen technologies are normally fixed at a certain resolution. If you increase resolution on these screens, the sharpness of the image will be greatly affected.
Overscan vs underscan
Most television manufacturers overscan the pictures on their displays. This is done to reduce on-screen picture from 720 x 576 to 680 x 550. The size of the invisible area may also depend on the display device. Computer displays do not overscan. Most of the projectors tend to be underscanned to compensate for any distortions at the corners.
Current standards
Televisions have different display resolutions including standard resolution, enhanced-definition resolution, high definition and ultra high definition. Ultra high definition televisions have the best display resolution. Most high end televisions are now using this display resolution.
Computer monitors have over time been known to posses higher resolution than television. As of July 2002, most commonly used resolution in computer monitors is 1024 x 768. Availability of inexpensive monitors has made 1028 x 1024 resolution more popular than any other display resolution. Other recently available resolutions include wide aspects such as 1440 x 900 WXGA+, 1280 x 800 WXGA, 1920 x 1200 WUXGA and 1680 x 1050 WSXGA+ and oversize aspects like 1400 x 1050 SXGA+. Recently, manufacturers have developed monitors with higher resolutions such as 2880 x 1800 for MacBook pro, 2560 x 1440, 2560 x 1600 WQXGA and 4086 x 2160 among others. Setting a computer resolution higher than the native resolution allows some video drivers to make the virtual screen scrollable over the native screen.