Groovy is a programming language that is specially created for Java developers with a view to being a fast-paced, scripting companion to Java. It aims to increase the productivity of Java developers by simplifying Java code and removing unnecessary boilerplate. Groovy not only present a succinct and easy to read syntax but also provide a much more elegant and convenient API than Java for common stuff. For example, a Groovy file can do in 50 lines what a Java source code does in 500 lines. You can declare an array as [] and map as [: ] which really makes code full of data without much syntax. Because of this property, Groovy is heavily used in unit testing of Java application. Some popular unit testing frameworks like Spock is also built on Groovy.