There are many manufacturers out there that make laptops. Each laptop manufacturer designs their laptop to be used with a variety of LCD panels. Depending on the specifications on the video card in the laptop, in order to fully use all the supported display modes, the LCD must support those resolutions also.
The main supported display types are:
VGA up to 640x480 resolution
XGA up to 1024x768 resolution
SXGA up to 1280x1024 resolution
SXGA+ up to 1400x1050 resolution
WXGA up to 1280X800 widescreen resolution
WXGA+ up to 1440X900 widescreen resolution
WSXGA+ up to 1680x1050 widescreen resolution
UXGA up to 1600x1200 resolution
WUXGA up to 1920x1200 resolution