Apache Velocity is an open source

Open source

The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...

 software project directed by the Apache Software Foundation

Apache Software Foundation

The Apache Software Foundation is a non-profit corporation to support Apache software projects, including the Apache HTTP Server. The ASF was formed from the Apache Group and incorporated in Delaware, U.S., in June 1999.The Apache Software Foundation is a decentralized community of developers...

. Velocity is a Java

Java (programming language)

Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...

-based template engine that provides a simple yet powerful template language to reference object

Object (computer science)

In computer science, an object is any entity that can be manipulated by the commands of a programming language, such as a value, variable, function, or data structure...

s defined in Java code. Its aim is to ensure clean separation between the presentation tier and business tiers in a Web application

Web application

A web application is an application that is accessed over a network such as the Internet or an intranet. The term may also mean a computer software application that is coded in a browser-supported language and reliant on a common web browser to render the application executable.Web applications are...

 (the model–view–controller design pattern).
Some common types of applications which use Velocity are:

• Web application
  Web application
  A web application is an application that is accessed over a network such as the Internet or an intranet. The term may also mean a computer software application that is coded in a browser-supported language and reliant on a common web browser to render the application executable.Web applications are...
  
  s: Web designers create HTML
  HTML
  HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....
  
   pages with placeholder
  Placeholder
  Placeholder may refer to:In language:* Placeholder name, words that can refer to objects or people, whose names are unknown or irrelevant* Filler text, shares some characteristics of a real written text, but is random or otherwise generated...
  
  s for dynamic information.