When a user requests a remote connection to the database it must first contact the listener. The listener redirects the request to the Oracle Instance. This will spawn a new Oracle Server Process, which from now on will be the process who will interface the user with the database; if the connection to the database is local to the machine, it may be established across the network or by Inter-Process Communication(IPC) , and the Oracle server process will be spawned too. This Oracle server process will be assigned to the user for the whole time the user remains attached to the database. The new user session will be assigned a Serial Number and a Session Id. These are the numbers used to uniquely identify a user connected to the database. The serial number guarantees that session-level commands are applied to the correct session objects in case a new session is started with the same SID. A user session can be initially monitored with the V$SESSION...