The hard drive in your PC comes preformatted from your PC manufacturer. However, in rare circumstances, you may need to reformat your hard drive. Reasons to reformat include: erasing old data from your hard drive, or repartitioning.

Most hard drives originally come with one partition, or one large unit for storage. This results in a very large cluster size which wastes almost half of your hard drive's space due to inefficient data storage.

But, you can divide your hard drive into several smaller partitions. This results in a smaller cluster size. The smaller the partition, the smaller the cluster size, which results in more efficient data storage. Each partition acts as if it were a separate hard drive, and is assigned a different drive letter.

To repartition your hard drive, follow the instructions in your operating system manual. After you repartition your hard drive, you will have to format each partition separately. See your operating system manual for instructions. You can also purchase hard drive management software that can repartition and reformat your hard drive all in one step.

The important thing to remember is that reformatting or repartitioning your hard drive will destroy all data on your drive. This is a drastic step and should be done with great caution!