If you are running Windows and would like to install Ubuntu on your system, you must free up some space on your hard drive (see How to Resize Windows Partitions) or install another hard drive on which to install Ubuntu. Changing the layout of a hard drive is called partitioning. There are various Partitioning Schemes that can be used to divide a hard drive.
For most people, it will be sufficient to use one of the "Guided Install" selections during installation of Ubuntu; however there are some circumstances in which manually partitioning your hard drive will be necessary. This guide will give you a basic understanding of manually partitioning your hard drive in preparation for Linux installation, as well as manipulating your partitions after it is installed.
The Ubuntu installer's Partition Editor, as well as the commonly used GParted partition manager, are some of the safest ways to partition a hard disk. However, it is nevertheless important to back up important files before using them.
In addition, removing unnecessary files and defragmenting a hard drive is worthwhile before manipulating partitions, in the interest of gaining free space and reducing the time necessary for the partitioning operations.