Most web applications are changed and adapted quite frequently and quickly. Their environment, for example the size and the behavior of the user base, are constantly changing. What was sufficient yesterday can be insufficient today. Especially in a web environment it is important to monitor and continuously improve the internal quality not only when developing, but also when maintaining the software. Jenkins is the leading open-source continuous integration server. Thanks to its thriving plugin ecosystem, it supports building and testing virtually any project. This book explains how you can leverage Jenkins to monitor the various aspects of software quality in a PHP software project.