text: Add-ons releases Software Collections (SCL) is a CentOS repository that provides a set of programming languages, database servers, and various related packages. Provided software versions are either more recent than their equivalent versions included in the base CentOS distribution, or are made available as official CentOS packages for the first time. (See also the list of CentOS repositories below.)
  Packages available from the SCL do not replace the default system tools provided with CentOS. Instead, a parallel set of tools is installed in the  directory, and can be optionally enabled per application by using supplied  utility. For example, the default versions of Perl or MySQL remain those provided by the base CentOS installation.
  Releases without upstream equivalents
  Some of the ISO images released by the CentOS Project have no direct upstream equivalents. They are created for specific purposes, such as for providing a live bootable image, or for providing a reduced-size installation medium.  In addition to those listed below, there are also AltArch releases, which also have no direct upstream equivalents.
  LiveCD and LiveDVD images contain a bootable compressed file system, created by a set of custom scripts using a kickstart configuration file. These live images can be also installed to hard disk, thus obtaining a fully functional CentOS installation. The set of packages installed that way on a hard disk can not be adjusted during the installation, as that is a simple transfer of the image existing on CD/DVD, to a hard disk. After booting from hard disk, yum can be used for adding or removing packages.