Install Method Explanations
There are two primary ways of installing Ubuntu on a computer and is dependent on each computer.
1. Fresh Install
~Install of one OS on a computer as the only OS~
The usual Fresh Install uses the entire hard disk drive for simplicity. Fresh install is used
to remove and replace a previous OS on a computer. It is also used for empty computers that have
no OS installed on them. It can sometimes be cheaper to purchase a used or new computer with no
OS and then install Ubuntu as the primary OS.
2. Dual Boot
~Install of a secondary OS on a computer~
The Dual Boot option is common for users who enjoy the Ubuntu OS but still need to use
certain programs within Windows or Macintosh that cannot be replaced with Ubuntu. The process is
fairly simple and after install, a menu option allows you to select which OS you would like to boot.
With dual boot, you have the choice of installing Ubuntu on a new, empty hard drive, or on the existing hard drive that Windows or Mac is saved. If it is the existing hard drive, less memory will be available to Windows or Mac after the install of Ubuntu. Ubuntu will be absorbing the memory from the hard drive.
I suggest having a new hard drive physically installed and then installing Ubuntu on the new hard drive. It will make the process easier and more secure.