Lumens are a measurment of light

Lumens often is referred to when talking about either over head projectors or data (digital projectors) for using with computers or DVD players, VCRs, etc This is referring more or less in english to how bright or intense the picture is the highter the lumens rating the more likely it is that you will be able to use the projector in daylight to watch DVD's some have low ratings and this means you have to pull the blinds or watch at night or have a high reflective screen. Teh higher the lumens the better and stronger the picture. Though LCD projectors can burn out and tend to not last quit as long as VGA projectors which have red blue and yellow bulbs in them to mix the picture together to create movie theatre quality pictures. they also don't rely on having to replace bulbs if you bump them which in some cases with LCD projectors can cost half of the purchase price sometimes up to $800.00 VGA is considered older technology, It's up to you if you are looking at purchasing an LCD projector and you want to watch in daylight or connect to a VCR and use in place of a TV if your wall is going to be the projection surface and it's painted with a matt paint get a projector with a higher lumen rating. Hope this helps for more info try www.howstuffworks.com a very well known and useful site often recommend and used by universities and high schools for more in depth info of how nearly everything you can thing of works