What is matrix or zone metering in photography?

Metering that mixes the results of several points around the central area of the focusing screen and presents one value that represents an aperture/shutter combination to use. To say these points are averaged would not usually be correct because different areas influence the result more than others. This is known as weighting, as in "central averaging, bottom weighted" in one system. Different manufacturers have different approaches to the problem of metering.