In photography, the shutter-release button (sometimes just shutter release or shutter button) is a push-button found on many cameras, used to take a picture. When pressed, the shutter of the camera is "released", so that it opens to capture a picture, and then closes, allowing an exposure time as determined by the shutter speed setting (which may be automatic). Some cameras also utilize an electronic shutter, as opposed to a mechanical shutter.
The shutter-release button is one of the most basic features of a handheld camera. Camera phones that lack a physical button for this purpose use a virtual button on the virtual keyboard.
The term "release" comes from old mechanical shutters that were "cocked" or "tensioned" by one lever, and then "released" by another. In modern or digital photography, this notion is less meaningful, so the term "shutter button" is more used.