Available on almost every digital camera, a flash (or strobe) allows you to illuminate subjects by using a short burst of light. Nearly all have auto-flash modes, a setting that will automatically fire a flash whenever the camera senses there isn't enough illumination for correct exposure. Most include other flash modes, including red-eye reduction mode, which minimizes a common flash camera problem (although you can also fix this in an image-editing programme when the image is stored on your computer). There are primarily two types of flashes associated with consumer-level cameras: a built-in (onboard or, in some cases, popup) strobe that is generally positioned directly or diagonally above the lens. An external strobe, sold separately as an accessory, fits into a camera's hot shoe, which lets you attach this accessory on to an advanced point-and-shoot. Many cameras include a number of flash modes that allow you to alter the type of flash or the strength of the illumination.