This document compares static and dynamic typing in Groovy and Java. Static typing catches errors earlier through compile-time type checking, while dynamic typing allows for more flexibility through duck typing and domain-specific languages. The document argues that for many modern applications, the benefits of dynamic typing in Groovy outweigh the advantages of static typing in Java, though static typing is still useful in some cases. It provides examples of design patterns that are reviewed when using a dynamic language and notes that performance is not necessarily better in Java.