A process that resides on the server whose responsibility is to listen for incoming client connection requests and manage the traffic to the server.
When a client requests a network session with a database server, a listener receives the actual request. If the client information matches the listener information, then the listener grants a connection to the database server.
A configuration file for the listener that identifies the following for a listener:
A utility included with Oracle Network Services to control various listener functions, such as to starting, stopping, and getting the status of the listener.