A hard drive is not always used as a single drive, but is often split up into multiple parts. This is accomplished prior to formatting, in a process called partitioning. As the name indicates, a hard drive partition is a part or section of the drive, treated by the operating system as an independent storage area or drive. Hence, a 120-gigabyte (GB) drive can be divided into several drives, rather than being used as one large drive.
This is handy for a number of reasons. For example, one can use a separate hard drive partition to install an alternate operating system (OS). If the two systems require different formatting schemes, this configuration can accommodate that. Programs and data can exist on a third partition to be used by either OS — whichever is active. A boot loader on the C:\ drive allows the user to choose which OS will boot.
Many people like creating a separate partition for the OS, even when there is only one present. By loading the OS into the C:\ drive and the programs into the D:\ drive, for example, the C:\ drive can be reformatted and the OS reinstalled, if need be, without losing programs or their settings and data. Creating multiple partitions also allows one to organize, maintain and utilize large hard drives better. A division that does not include the entire disk can be defragged or scanned much faster than a larger one. When programs, data and multimedia content are stored on their own partitions, they can also be archived easily on backup drives as needed.
Partitioning is commonly accomplished with the fdisk command. Alternate methods include graphical tools. While the partitioning scheme only allows four primary partitions, more can be created as extended partitions. Hence, any number is possible.
One example of a 120 GB drive made into several partitions is as follows:
| C:\ | [10GB] | Operating System | Hard Drive Partition #1 | |
| D:\ | [20GB] | Programs | Hard Drive Partition #2 | |
| E:\ | [10GB] | Data Files | Hard Drive Partition #3 | |
| F:\ | [80GB] | Ripping/Burning Multimedia Storage | Hard Drive Partition #4 |
Partitioning a hard drive will cause all data to be lost. Before creating one on a disk already in use, be sure to backup all data. Thoughts, advice, and how tos on various partitioning strategies are available from many tech sites.