The CentOS Distribution is a free enterprise class computing platform
to anyone who wishes to use it.  The CentOS Distribution is built from
publicly available open source SRPMS provided by a prominent North
American Enterprise Linux vendor.  The CentOS Distribution conforms
fully with the upstream vendors redistribution policies and aims to be
100% binary compatible (The CentOS Project mainly changes packages to
remove upstream vendor branding and artwork.).

The CentOS Project releases its CentOS Distribution as a GPL work. The
GPL applies to the software collection known as the CentOS
Distribution.  Individual packages included in the distribution
include their own licenses and the GPL applies to all packages that it
does not clash with. If there is a clash between the GPL and
individual package licenses, the individual package license applies
instead.

Neither the CentOS Project (we who build CentOS Distribution) nor any
version of CentOS Distribution is affiliated with, produced by, or
supported by the prominent North American Enterprise Linux vendor.
Neither does our software contain the upstream vendor's product ...
although it is built from the same open source SRPMS as the upstream
enterprise products.