Software metrics are units of measurement of software. In this definition, software includes both the product (programs, documentation, reports) and the process by which the product is developed (the software life cycle phases of specification, design, implementation, testing, and maintenance). Software metrics make it possible for software to be compared, evaluated, and analyzed quantitatively. Example software metrics and related measures are program size (source lines of code), efficiency (execution time), reliability (mean time to failure), and programmer experience (years of programming in a particular language). Metrics and measures form the basis for numerous models of the software development process.

Patricia B. van Verth. 2003. Software metrics. In Encyclopedia of Computer Science (4th ed.), Anthony Ralston, Edwin D. Reilly, and David Hemmendinger (Eds.). John Wiley and Sons Ltd., Chichester, UK 1627-1631. [ACM Digital Library]