Software metrics, an area of software engineering, is concerned with various measurements of computer software and its development. Software metrics, its importance, some current areas of investigation, and problems are described. An annotated bibliography of work in software metrics is included.I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind: it may be the beginning of knowledge, but you have scarcely, in you thoughts, advanced to the stage of science , whatever the matter may be.---Lord Kelvin, Popular Lectures and Addresses , volume 1, 1889