Work with Partitions

Most hard disks are known by a single drive letter, usually C:. However, any drive can be divided into several partitions, each with its own drive letter.

Most PC manufacturers these days ship partitioned hard disks. In fact, your drive may have one primary partition with all your data, plus another, smaller partition containing your PC's recovery data (to restore your hard disk to the state it was in when you bought it), and sometimes a third EISA Configuration partition (discussed later in this tutorial). If you decide to nix the other two partitions, you can combine them and finally start using all the space on your drive.

But you also may want to chop up your drive into smaller partitions. For example, if you have a 500 GB hard disk, you may choose to divide it up into four 125 GB partitions, or perhaps a 300 GB partition and two 100 GB partitions. There are a bunch of reasons why you might want to do this:

Organization
Use multiple partitions to further organize your files and make your stuff easier to find. For example, put Windows on one drive, work documents on another, games on another, and music and other media on yet another.

Isolation of system and data
You can use partitions to isolate your programs from your data. For example, place Windows on drive C:, your personal documents on drive D:, and your virtual memory (swap file) and temporary files on drive E:. This setup gives you the distinct advantage of being able to format your operating system partition and reinstall Windows without touching your personal data, and also makes it easier to back up just your data.

Performance
As illustrated in "A Defragmentation Crash Course" earlier in this tutorial, the data on your hard drive can become badly fragmented with use, which hurts performance and increases the chances of data corruption. Because files cannot become fragmented across partition boundaries, you can dramatically reduce fragmentation by separating frequently accessed files, like those in the Windows and Program Files folders, from frequently updated files, like your virtual memory (swap file) and temporary files, as well as infrequently updated files like photos and music. But because fragmentation increases as free space decreases, you'd only get these performance gains with a drive large enough to guarantee sufficient free space on every partition.

Dual-boot
To set up a dual-boot partition, you'll need to create a separate partition for each operating system you install.

Server
If you're setting up a web server (or other type of network file server) or if you're participating in peer-to-peer file sharing, it's a good practice to put the publicly accessible folders on their own partition. This not only helps to secure the operating system from unauthorized access, but allows the OS to be upgraded or replaced without disrupting the shared folders and programs.

Naturally, there's a downside to having multiple partitions. For one, since you have to assign portions of your drive to different tasks ahead of time, multiple partitions use your space less efficiently than one big partition. Next, if you're the indecisive type and find yourself frequently rearranging your files, moving files between partitions takes much longer than moving files between folders on the same partition.