|Digital SLR Camera|
DSLR is an acronym for "Digital Single Lens Reflex". A digital SLR camera has two distinguishing characteristics. 1) It uses a mirror and prism to show the scene that the lens sees through an optical window viewfinder. Here's a diagram:
|Light travels through the lens, bounces off the mirror, though the prism and out the viewfinder in a DSLR camera|
When you press the shutter button to take the photo, the mirror moves up, toward the prism, to allow the light coming through the lens to travel straight back to the sensor (or film).
2) A DSLR camera allows for different lenses, such as a wide-angle lens or a telephoto lens, to be easily exchanged to produce different views of the scene.
|Sony DSLR with two lenses|
A mirrorless digital camera also provides the capability of swapping different lenses for different effects. But unlike the DSLR, it does not have the mirror and prism design, hence the name. Instead, the mirrorless camera most often shows the image the lens sees by displaying it on the LCD screen on the back of the camera body. (Some models provide an electronic viewfinder in addition to the LCD screen.) This is what contributes to the mirrorless camera's smaller size.
|Mirrorless digital camera|
A compact or "point & shoot" digital camera has a fixed lens; while it might zoom, you can't remove it and put another lens on in its place. A compact camera shows what the lens sees on the LCD screen (or sometimes a window or electronic viewfinder) like a mirrorless camera. A compact digital camera can have very simple controls or the ability to change many settings like a DSLR or mirrorless camera.
|Compact digital camera|
Recently, cell phone cameras have replaced compact digital cameras in popularity in the marketplace.
|Camera phones are more common than compact digital cameras|
If you are shopping for a digital camera, deciding which type meets your needs can be daunting. The people at Digital Photography Review have written a good article on the pros and cons of DSLR versus mirrorless cameras: "Why buy an interchangeable lens camera?" Before making your final decision, try to handle the different types of cameras and take a couple shots with each. All can make good pictures, but you will like the feel of one over the others and no review can tell you that.
If you are interested in taking a class on digital photography, it is helpful to know what kind of camera you own and what type of controls it provides. Both mirrorless and DSLR cameras provide the ability to manually adjust exposure, color, focus and other controls to give you more creative options. Only a few compact cameras offer controls similar to those on DSLR or mirrorless models.
If your digital camera provides the ability to change the shutter speed, aperture and ISO (sensitivity) settings, you can learn how and why to change them in "Getting to Know Your Digital SLR Camera" beginning September 20, 2016.