A chroot environment is simply a directory – inside which you can find a file system hierarchy exactly like your original operating system. You can then use the UNIX
chroot command to open a shell in that directory so that command running under that shell see only the chroot environment and can’t mess up your system. This is very useful for many different reasons – for example if you want to build some software packages and you don’t want their build dependencies to pollute your real system.
Building a chroot environment is not difficult at all using the right tools, and YUM – the CentOS installation tool – has what you need.