Shaking your camera is usually a bad things. Let's explore some ways to make it stop moving.
When you take a picture with a handheld camera, you push a button and the camera does some stuff. When you put it on a tripod and push the button, the camera moves a bit before settling down as it's doing the stuff. This means the beginning of your exposure is likely going to suffer from some focus or motion blur because your camera is literally moving at the time. Not a big deal for a 1/2000 second sports exposure but this is horrible for an astrophotography session. Plus, this shake is on top of the shake caused by mirror flip from the mirror of a DSLR camera as it flips up and down to let light onto the sensor or up to the viewfinder. We can't stop a DSLR from doing mirror flip (see below, however) but we can stop the camera from shaking when we push the button on a tripod.
All of this is great for dealing with the shake created by pushing the button, but does nothing about the "mirror flap" caused by the reflex mirror flipping out of the way. As long as you're using a DSLR, you can't really do anything about it becauause that's how they work. However, if your camera has a Live View mode, then it basically converts it into a poor-man's mirrorless camera and the mirror flips up for as long as you have Live View mode active. This solves the mirror flap problem as well.