Are all single-lens cameras SLR? What's the difference between SLR and ordinary digital camera?

Single lens is our common camera with only one lens, which is only a necessary condition for SLR cameras; Ordinary cameras are basically single lens. I only remember seeing the double lens and playing the seagull card for a while when I was a child.

We commonly call SLR a single-lens reflex digital camera, which means that when shooting scenery, it is shot through the main lens of the camera and reflected into the eyepiece through the reflex mechanism. In other words, what you see through the eyepiece or display screen is the final image taken by the main lens, which is inverted through the main lens through the SLR mechanism.

The powerful performance and photographic quality of SLR are mainly due not only to the relatively accurate front view, but also to the larger and better sensor chip than ordinary cameras, which is equivalent to the retina of the eye. Other accessories, such as various lenses, multiply the comprehensive performance and are necessary for professional photography.