Next we are going to discuss the Oracle Home directory.
When you install Oracle software, you end up with a large directory structure that contains all the executables and other files that make Oracle work. All these directories sit under one top-level directory referred to as the Oracle Home directory. The diagram below shows some of the directories that you might find in a typical installation. Move your mouse over the diagram to learn about each directory:

If you are running the UNIX operating system, you will have an environment variable named ORACLE_HOME that points to the top-level Oracle directory. You can make that directory your current working directory by issuing the following command:

cd $ORACLE_HOME

If you are running Oracle8 software under Windows, and if you accepted all the defaults when first installing Oracle, your home directory will be one of the following:

If you currently have access to Oracle8, take a moment now to be sure that you can find your Oracle Home directory.

By default, when you start Oracle Universal Installer, the software searches your system to determine the default Oracle home where Oracle software should be installed.
In all cases, the ORACLE_HOME name is taken first from the command line if it is specified, or else from the response file if specified.