The DSLR System
A Digital Single-Lens Reflex (Or DSLR) has a mirror that reflects the scene through a prism, and then through to the viewfinder. This gives the photographer an actual live view of what’s going on. When the shutter button is pressed, the mirror flips out of the way (a reflex) and a photo is exposed/taken.
Advantages of The DSLR System
LOTS OF GEAR TO CHOOSE FROM
The DSLR has been around for a long time so there are lots of cameras, lenses, and accessories available. Many DSLR cameras are “mature” - meaning that the camera model you’re buying isn’t the manufacturers first try. They’ve had a long time to work out all the bugs. You have a great supply of new and used gear on the market. Mirrorless systems are starting to catch up, but they’re not there yet.
OPTICAL VIEWFINDER (OVF)
Most DSLR cameras use an OVF. With an OVF, an actual live view of the scene is visible. The photographer is seeing the actual scene in real-time. Most mirrorless cameras use an electronic viewfinder (EVF). A digital version of the scene. Some cameras offer both OVF and EVF, or a hybrid. This is awesome and you should check them out!
A DSLR, in general, has fewer electronics. Which means a longer battery life. Mirrorless cameras come with a catch... All of that electronic technology comes with a price tag - battery life!