Resolution is the number of pixels or elements that make up the image from a projector. The common ones for business projectors - which have a 4:3 aspect ratio are:

SVGA: 800 columns by 600 lines.
XGA: 1024 columns by 768 lines.
SXGA: 1280 columns by 1024 lines.
SXGA+: 1400*1050

If you are thinking of purchasing a projector to use with a laptop or PC then it's always best to try to match the projector resolution to the PC's resolution.

Home cinema projector are generally 16:9 aspect ratio and we quote the resolution as video with the actual figures in brackets.

The figure we quote under Resolution is native to the projector. Under Computers you'll find the other resolutions supported by each projector.