The service phase of the Servlet life cycle represents all interactions with requests until the Servlet is destroyed. The Servlet interface matches the service phase of the Servlet life cycle to the service() method. The service() method of a Servlet is invoked once per a request and is responsible for generating the response to that request. The Servlet specification defines the service() method to take two parameters: a javax.servlet.ServletRequest and a javax.servlet.ServletResponse object. These two objects represent a client's request for the dynamic resource and the Servlet's response to the client. By default a Servlet is multi-threaded, meaning that typically only one instance of a Servlet1 is loaded by a JSP container at any given time. Initialization is done once, and each request after that is handled concurrently2 by threads executing the Servlet's service() method.