The size of the monitor screen is measured in inches across the diagonal. The screen size must be proportionate to the resolution of the screen for achieving the maximum utilisation of the desktop and details of the image.
Mainly two forms of LCD monitors are available: with standard width and height proportion 4:3 or the widescreen proportion 16:9 or 16:10. A widescreen monitor is wider and its resolution is higher than that of the monitors with standard proportion.
The bigger the monitor size the higher resolution usually is supported. Possibilities to increase the resolution of the screen usually depend on the size and possibilities of the monitor and the type of the video card.