DSLR Cameras

Digital Single Lens Reflex Cameras - DSLR Cameras.
DSLR is the acronym for Digital Single Lens Reflex Cameras. Most of the professional photographers use this type. Anyone using compact cameras would never have used the viewfinder. The LCD display provides a live preview of the subject. In DSLR cameras, the viewfinder is often used although many DSLR cameras provides a LCD disply. This is because the SLR system allows one to see through the lens. Hence one can have a view of the subject exactly as it would be captured by the sensors.
Unlike other digital camera models, DSLR has virtually no shutter lag. The image is captured exactly at the moment you click. This is highly an important factor in action/sports/wildlife photography when the subject is in motion. The start-up time of DSLR cameras are quicker than compact or bridge cameras. DSLR allows to manually control almost every feature from Focus to White Balance.
For more technical detail on how Single Lens Reflex system functions, see the article in wikipedia. This has some simple but detail illustrations.