I use Oracle VM VirtualXbox. It is a program developed by Oracle which let's you run Virtual Machines.
It means that you can run other Operative Systems and have more computers inside your computer without having to dual-boot or make partitions for the other OS's.
It is not too practical if you plan to use another OS as main.
So for my programming classes they asked me to download Linux Fedora and many other OS's, all my classmates had lots of problems with their laptops, but I simply downloaded all OS's and ran them on VirtualBox, and worked like a charm.