Pan, Tilt, Zoom cameras allow you to sweep left and right, go up and down, and zoom in on your target. You can control what the camera does via your computer, DVR, or a remote control. Just like you see in casinos, you can follow a person around to see what they're up to.
When monitoring a parking lot, you can follow a person to their vehicle and zoom in on the license plate.
In a store, you can zoom in on the face to get a close up, see what they have in their hand or cart, and other wise keep tabs on a suspicious person.
These high end PTZ cameras have high resolution, extreme zoom features, and can even see in the dark.