macro lens: A lens that provides continuous focusing from infinity to extreme close-ups, often to a reproduction ratio of 1:2 (half life-size) or 1:1 (life-size).

marquee: The dotted outline that results when you select a portion of your image; sometimes referred to as marching ants.

masking: In an image editor, selecting an area of an image to prevent that area from being modified accidentally.

matrix metering: Also called multizone metering. A metering mode that calculates exposure based on the entire frame.

megapixel: One million pixels.

memory card: A camera’s removable storage media.

metadata: Extra data that gets stored along with the primary image data in an image file. Metadata often includes information such as aperture, shutter speed, and EV setting used to capture the picture, and can be viewed using special software. Often referred to as EXIF metadata.

metering mode: Refers to the way a camera’s autoexposure mechanism reads the light in a scene.

Microsoft PowerPoint: A multimedia presentation program.

midtones: Parts of an image with tones of an intermediate value, usually in the 25 to 75 percent range.

modeling lights: Incandescent lamps built into a studio flash that give you a preview of exactly how the light from the flash will look.

modular belt system: A belt that can hold a variety of photography equipment.

monopod: A one-legged support, or unipod, used to steady the camera.

multiple auto-focus: A setting that allows the camera to find more than one area of contrast to focus on.

multiple-exposure: A technique in which a small aperture gives you a long exposure, allowing your subjects to move within the frame during shooting, which creates a photo that looks like it has been exposed more than once.