The era of information technology has been revolutionized with the explosive increase in the number of deployed open source software. Many countries in the world are now adopting policies that are favorable to open source, because open source software can be seen as tool for economic development. As the group of people and organizations that depends on open source software technologies continues to grow, it becomes increasingly important to have an insight into the evolution and code decay aspects of open source software. This book provides an in-depth analysis of code decay for many different categories of open source software. The book would be useful for practitioners and researchers working in the field of open source software.