Developing large scale software is a challenging task. With the growth in size and complexity of software and open source technology the role of software metrics becomes more important. This book comprehensively presents the essential software metrics for various phases of the software development lifecycle. It also covers the linking of metrics model with the quality of software and defining guidelines for various phases of development of software. Practical example, with real-time software linked with software development metrics and the defects, are modelled and discussed. The aim is to introduce the readers to the software metrics and its use in software quality modelling and measures.