HttpServletRequest, ServletRequest, request

The Request|servlet HttpServletRequest interface is inherited from the ServletRequest interface. Added some of the methods associated with HTTP.
The so-called request (used in JSP) is actually only a name in the specification. It is of course an object, but it is not sun-supplied, it is written by various servlet providers, and Sun simply prescribes that the class implements the HttpServletRequest interface and specifies the purpose of each method, but specifically what class is determined by each provider.
You can use OUT.PRINTLN (request) in the JSP to see the name of this class.