In most cases, you will be using an application called Yum to work with packages on CentOS.
Yum — Yellowdog Updater Modified — was originally created for a Linux distribution called (perhaps obviously) Yellowdog, but probably due to its “user-friendliness” it has been taken up by other distributions such as CentOS and Fedora, etc.
Unlike the original Redhat Package Manager (RPM), Yum will automatically download/install from a software repository on the internet, or from a CD/DVD, just using a package name. With RPM you either have to download the file locally first and/or supply the full file system path or URL to the file.
So how do we install a package using Yum? It’s really quite simple; you use the following:
yum install packagename
It’s quite self-explanatory, really. The “packagename” is the name of the package; you do not use the version numbers or any extensions.
Yum will check if other packages/software are required if so, it will add them to the list of packages to be installed. All you have to do is to confirm you want to continue when prompted.
You can see an example in this article on installing dig.
RPM
Using RPM is a little bit more involved, and sometimes you need to use it when Yum can’t help.