Oracle Database is an object-relational database management system[3] produced and marketed by Oracle Corporation.

As you asking here I am providing info related to Oracle DB 11G

Oracle Database 11g Release 1: 11.1.0.6–11.1.0.7 (Patchset as of September 2008)

Oracle Database 11g Release 2: 11.2.0.1–11.2.0.4 (Patchset as of August 2013)

Oracle Corporation released Oracle Database 11g for Linux and for Microsoft Windows in 2007

Oracle 11g Express Edition, released by Oracle Corporation on 24 September 2011,can support 11 GB of user data.Oracle XE does not support loading Java code into the database.

As of November 2011, Oracle Corporation supported the following operating systems and hardware platforms for Oracle Database 11g (11.2.0.2.0):
zLinux (64-bit)
Microsoft Windows (32-bit)
Microsoft Windows (x64)
Linux x86
Linux x86-64
Solaris (SPARC)
Solaris (x86-64)
HP-UX Itanium
HP-UX PA-RISC (64-bit)
AIX (PPC64)
OpenVMS (IA64)[88]

As of 2013 database options include:
Active Data Guard (extends Oracle Data Guard physical standby functionality in 11g)
Oracle GoldenGate 11g (distributed real-time data acquisition)
Oracle Real Application Testing (new at version 11g)—including Database Replay (for testing workloads) and SQL Performance Analyzer (SPA) (for preserving SQL efficiency in changing environments)

Oracle Multimedia (known as "Oracle interMedia" before Oracle 11g) for storing and integrating multimedia data within a database
Oracle Spatial and Graph