The website www.centos.org says: “The CentOS Linux distribution is a stable, predictable, manageable and reproducible platform derived from the sources of Red Hat Enterprise Linux (RHEL) … Since March 2004, CentOS Linux has been a community-supported distribution derived from sources freely provided to the public by Red Hat. As such, CentOS Linux aims to be functionally compatible with RHEL.”
In the FAQ section of the CentOS website there is more information about Centos in general as follows (just a few short comments): CentOS Linux provides a free and open source computing platform to anyone who wishes to use it. CentOS Linux is the Community Development Platform for the Red Hat family of Linux distributions. CentOS Linux is NOT supported in any way by Red Hat®, Inc. CentOS Linux is built from publicly available source code provided by Red Hat®, Inc. The upstream provider offers Enterprise Linux in several flavors, AS, ES, WS, PWS, etc. CentOS is like the AS version.
To download CentOS 7 you click the Get CentOS Now button. Click the DVD ISO button. Click on one of the mirrors listed. The file is 4.1GB in size so expect it to take some time to download.
Regarding the mouse, press the right Ctrl button to get the mouse out of the VirtualBox into Windows. It’s a little awkward at first and it takes a few times doing it to get used to it. To get the mouse working again in the VirtualBox just click inside the virtual window and it will appear as a solid black mouse pointer instead of your regular pointer.
Regarding shutting down CentOS Linux, go to the Terminal and type poweroff and press Enter.
Udemy Course – Introduction to Linux
To dig a little deeper into Linux you might consider taking a course at udemy.com. One such free course is called Introduction to Linux by Muhammed Torkey.