The document discusses continuous improvement in PHP projects. It defines concepts like continuous integration, inspection, and delivery. It emphasizes that continuous improvement is an ongoing effort to iteratively improve products and processes. The document recommends using agile methods like Scrum and extreme programming (XP) to integrate continuous improvement into daily work. It also discusses tools like Jenkins, PHP_CodeSniffer, PHPMD, and PHPUnit that can help with continuous improvement. Common PHP project problems like code aging and technical debt are addressed, and paying down technical debt through constant refactoring is advised.