A disk partition allows you to take one big hard drive and divide it into multiple virtual hard drives. You could, for example, dual-boot Windows and Ubuntu by installing one operating system on each partition. You could also have your operating system on one partition and keep all your data on another partition.
Examining the Hard drive Layout
One way to understand the system drive structure is to use a tool supplied with Windows System called Disk Management, a snap-in that's part of the Microsoft Management Console. The majority of systems sold today for home or small Professional use will come equipped with one hard drive; although many manufacturers offer special deals on new systems that make it financially attractive to add a second, third, or even fourth hard drive if you have a need for the extra capacity. In spite of the fact that a single hard drive can be configured in many different ways, it's a pretty safe bet that an off the shelf system will arrive in one of two basic configurations: either the entire drive will be partitioned as C: as shown in Fig. 01 or it will be split into two partitions, one as C: that is visible and another partition that is hidden and contains an image of the operating system (and a ton of useless software) in case things go terribly wrong requiring a reinstall of the operating system.
Disk Management can support some simple drive partition management. But all these operations are at a risk of data loss. So if you want to partition your hard drive, you need turn to a 3rd party partition management software.