What is EPEL?
Extra Packages for Enterprise Linux (EPEL)
Extra Packages for Enterprise Linux (or EPEL) is a Fedora Special Interest Group that creates, maintains, and manages a high quality set of additional packages for Enterprise Linux, including, but not limited to, Red Hat Enterprise Linux (RHEL),CentOS and Scientific Linux (SL).
EPEL packages are usually based on their Fedora counterparts and will never conflict with or replace packages in the base Enterprise Linux distributions. EPEL uses much of the same infrastructure as Fedora, including buildsystem, bugzilla instance, updates manager, mirror manager and more.
As part of the Fedora packaging community, EPEL packages are 100% free/libre open source software (FLOSS).
How to ues these extra packages?
EPEL has an 'epel-release' package that includes gpg keys for package signing and repository information. Installing this package for your Enterprise Linux version should allow you to use normal tools such as yum to install packages and their dependencies. By default the stable EPEL repo is enabled, there is also a 'epel-testing' repository that contains packages that are not yet deemed stable.
NOTE for RHN users.
You need to also enable the 'optional' repository to use EPEL packages as they depend on packages in that repository. This can be done by enabling the RHEL optional subchannel for RHN-Classic. For certificate-based subscriptions see RHEL Deployment Guide
If you are running an EL6 version, please visit here to get the newest 'epel-release' package for EL6: The newest version of 'epel-release' for EL6
If you are running an EL5 version, please visit here to get the newest 'epel-release' package for EL5: The newest version of 'epel-release' for EL5
You can verify these packages and their keys from the Fedora project's keys page: https://fedoraproject.org/keys
Install the epel-release RPM package
For example, Oracle Linux 6 x86-64
rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm yum update yum install foo