Oracle Enterprise Manager (OEM or, often, EM) is a web-based interface for controlling an oracle database. It allows a Database Administrator to perform the majority of their tasks such as creating users, tablespaces, roles, jobs, etc. as well as including visual performance monitoring and analysis tools.
The latest version is 12c which is backwards-compatible to Oracle database versions 10 and 11.
This tag should be used for questions relating to the installation and use of this software.