I am studying Spring framework, in web.xml I added following which is a bootstrap listener. Can anyone give me a proper idea of what is a bootstrap listener? <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> You can see the doc here: ContextLoadListener Bootstrap listener to start up and shut down Spring's root WebApplicationContext. Simply delegates to ContextLoader as well as to ContextCleanupListener. This listener should be registered after Log4jConfigListener in web.xml, if the latter is used. As of Spring 3.1, ContextLoaderListener supports injecting the root web application context via the ContextLoaderListener(WebApplicationContext) constructor, allowing for programmatic configuration in Servlet 3.0+ environments. See WebApplicationInitializer for usage examples...