Visualizing the Complete Oracle Environment - Oracle 10g Database Administration Concepts and Implementation Made Simple - page 6

Session: Each connected User with Oracle Instance is considered
as one Session.
Instance: All users interact with Instance to retrieve or store
information.
Database: Is like the notebook where Oracle Instance writes the
information and is encrypted.
Users from all over the world can connect to Oracle Server
provided they have access. Based on the privileges they have,
users can store, retrieve information, and create new tables etc.
from any part of the world whether they are on wired network or
wireless network.
Things to Remember Before Moving Ahead
1) Oracle Server is comprised of two things
o Instance
o Database
2) Anything that is going into the database or coming out of
the database has to be through Oracle Instance.
3) To communicate with Oracle Instance we need to learn
SQL.
4) Oracle Database is encrypted and we cannot read it
through any Text Editor like MS Word.
5) SQL commands are used to store and retrieve
information.
6) Each connected user with Oracle Instance is considered
as “Session”