Oracle is a relational database management system (RDBMS) product. Specific releases of the product are known as Oracle9i, Oracle 10g and Oracle 11g. Generally there are two releases within each major version. Questions tagged "oracle9i" are assumed to be specific to this version or features introduced in this version.
Oracle is an RDBMS product. The software has undergone a number of releases, including 11gR1 and 11gR2. Questions tagged with oracle9i are assumed to be specific to this version or features introduced in this version. It is generally advisable to specify both the full database version (eg 9.2.0.2) and often useful to include the underlying operating system.
Questions should probably be additionally tagged oracle for the widest readership.
Questions about SQL in general should probably be tagged sql.
Questions about PL/SQL in particular should probably be tagged plsql as well as oracle.
Where the question relates to installation or operation, it may be more appropriate to post in Server Fault.