Making a selection or purchase of LCD projectors can be tricky if you don't know what to look for or how to ask for what you need. Knowing and understanding the proper LCD projectors key terms can help you communicate efficiently with a sales associate or customer service representative. LCD projectors key terms can include lumens, contrast, illumination, connectivity, aspect ratioand external peripherals. Lumens Lumens are the measure of the perceived power that light gives off. They refer to the measure of brightness in an LCD projector. Contrast Contrast helps differentiate objects from their background. Contrast in an LCD projector helps differentiate the color and brightness of two objects that are within the same field of view. Illumination Illumination refers to the application of light. Make sure that the illumination of your LCD projector fills the screen evenly and doesn't give you dark corners or dark spots. Connectivity Connectivity refers to what items your LCD projector will hook up to. Aspect ratio The aspect ratio is the height to width ratio of your LCD projection image. Standard images used to be 3x4, but many are changing to a 16x9 ratio. External peripherals External peripherals, sometimes referred to as confidence monitors or floor monitors, are monitors that are attached to the LCD unit that allow the presenter to see what is being presented without having to turn around. This is especially helpful for large-scale, big-production events, especially those that are being recorded for rebroadcast as they allow the moderator to keep all focus forward.