Velocity is an open source templating technology developed by programmers all over the world. It is a project of the Apache Software Foundation. Velocity uses its Java-based template engine to merge templates.
We can reference objects defined in Java code with the Velocity template language. A Velocity template thus can be used for user interface in web applications. As a result, Velocity helps achieve the separation of the presentation layer and the business logic implementation. It provides an alternative to JavaServer Page (JSP) and Hypertext Preprocessor (PHP).
Velocity can also be used to generate source code, format emails and transform XML files.