A JavaServer Pages compiler, or JSP compiler, is a program that parses JavaServer Pages

JavaServer Pages

JavaServer Pages is a Java technology that helps software developers serve dynamically generated web pages based on HTML, XML, or other document types...

 (JSPs), and transforms them into executable Java Servlets. A program of this type is usually embedded into an application server

Application server

An application server is a software framework that provides an environment in which applications can run, no matter what the applications are or what they do...

 and run automatically the first time a JSP is accessed, but pages may also be precompiled for better performance, or compiled as a part of the build process to test for errors.

Most JSP containers support configuring how often the container checks JSP file

Computer file

A computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished...

 timestamp

Timestamp

A timestamp is a sequence of characters, denoting the date or time at which a certain event occurred. A timestamp is the time at which an event is recorded by a computer, not the time of the event itself...

s to see if the page has changed. Typically, this timestamp would be set to a short interval (perhaps seconds) during software development

Software development

Software development is the development of a software product...

, and a longer interval (perhaps minutes, or even never) for a deployed 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...

.