Velocity
Velocity is a Java-based template engine used for generating dynamic web content, emails, configuration files, and other text-based output from templates. It separates application logic from presentation by allowing developers to embed references to Java objects in simple template files, which are then processed to produce the final output. It is part of the Apache Software Foundation and is widely used in web applications and other software projects for its simplicity and flexibility.
Developers should learn Velocity when they need a lightweight, easy-to-use template engine for generating text-based content in Java applications, such as in web frameworks like Apache Struts or Spring MVC for rendering HTML views. It is particularly useful for scenarios requiring clean separation of code and design, such as email templating, report generation, or configuration file creation, where its straightforward syntax reduces complexity compared to embedding logic directly in output code.