What kind of camera is the cannon that many reporters hang on their bodies?

Hard-working photographers usually use professional-grade SLR cameras for their work. The requirement is that the bottom (sensor) should be large, so that the size of the fuselage can be large, and then the function is strong, and the lens can be changed according to different shooting needs. Outdoor needs longer focal length, larger aperture, etc. What looks like a cannon in front is all kinds of telephoto lenses.