For those who are a bit lost with the word “partitions”, they are sectors in which your hard disk is divided.
You can divide your HD to have one OS in one partition and data on another, or add a partition just for back up data, and if you’ll be installing more than one OS in your system each one of them will have to sit in its own partition.
GParted (Gnome Partition Editor) is a wonderful open source application that will allow you to easily work with the partitions of your HD. You can add, delete, resize, copy, and move partitions all with an easy interface.
Run GParted on a live CD, USB, or inside your favorite Linux distro. If you’re running from an installed OS make sure though that the partitions you’ll be working with are not mounted.
Added bonus, GParted works with several file systems such as: ext, fat, linux-swap, ntfs, and more.
A very handy app to have, highly recommended.