Groovy is a new language based on Java that elegantly combines the advantages of traditional programming and scripting languages. Additional language constructs allow for a level of productivity not seen in Java. By eliminating unnecessary syntactic overhead from Java while maintaining full compatibility with existing Java libraries, the transition is also very straightforward. Groovy is particularly well-suited for XML processing, graphical user interfaces, and testing Groovy and Java applications. Web servers can also be implemented in just 25 lines of code. Groovy committer Joachim Baumann provides a comprehensive introduction to Groovy version 1.5, supported by numerous examples. Building on that, he addresses advanced topics such as the Meta Object Protocol and Groovy's own Builder infrastructure.