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What is a C: Drive?

By R. Kayne
Updated: May 16, 2024

In computers, active storage drives are automatically assigned a drive letter, beginning with the letter A. The DOS operating system followed the drive letter with a colon, as in A: . Prior to flash memory devices, computers incorporated floppy disk drives for portable storage, so the A and B drive letters were preserved by the system to be assigned to these devices. This left C as the first letter available for the hard disk. So it is that the hard disk became known as the C: drive.

In days past hard disks were small enough that they were not divided into partitions, so a single drive letter was all that was required. The operating system was always installed on the C: drive and virtually all instructions for software and device drivers also referred to by this name. Today it’s a different story.

Today’s hard disks are often several hundred gigabytes, or even as much as a terabyte, and growing. Generally, computer users find that dividing large disks into several partitions or sections is handy for organization. In some cases it is even required by the computer’s BIOS and/or operating system. With each additional partition created on the drive, the system assigns a new, sequential drive letter that it handles as a separate storage device. Thus, a “C: drive” today might only refer to a very small portion of a much larger disk that houses several additional drive letters.

With the proliferation of computers came exploitation by malicious hackers, malware, viruses and spyware. The C: drive is the common target because it is the default drive for installation of the operating system. For this reason some people with an eye for security choose to create a small C: drive to hold a few DOS utilities and other files, but install the main operating system on the D: drive. While this certainly doesn’t guarantee freedom from hackers, viruses or malware, it does automatically eliminate those threats that target the drive as the place where the operating system will be found.

Before partitioning a new hard drive, it might be helpful to read about the different strategies people are using to minimize risks, organize data, and accommodate different operating systems and purposes. Creating a C: drive that is drastically reduced in size and retired from key use is probably a wise option. However, games made for DOS will require installation on the drive, so if you will be using these be sure to allocate enough space. Also, some older software packages install automatically to the C: drive regardless of where the operating system is located.

EasyTechJunkie is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
By anon940400 — On Mar 18, 2014

My computer is telling me to free up space on the C drive. I have tried over and over again, but now it has zero bits.

By anon350029 — On Oct 01, 2013

Can I access my C drive via the desktop right click menu?

By anon319810 — On Feb 14, 2013

when i click on my computer c drive has a bunch of letters and numbers in front.. 81E5 DHGTIFRTTTTTTTTPOTRRTRTHHH (c:) I don't remember seeing this before. Can someone tell me what's up?

By anon138311 — On Dec 31, 2010

I'm sorry, this is a very bad question, but i couldn't find it on the article, maybe i wasn't looking very good, are computer games downloaded on the C: drive? Thank you whoever can answer.

By anon135640 — On Dec 19, 2010

My laptop keeps telling me that I am running low on disk space on (C:) (C Drive) but when i go to 'My Computer' to free some stuff on their, i can't find the link for (C:) and i can't find it anywhere on my computer, any help?

By anon45504 — On Sep 17, 2009

What does "Drive C: is not writable" mean? How can I make it "writable"?

By anon45090 — On Sep 13, 2009

I have 100589 bytes. what does that mean in computer talk?

By anon38239 — On Jul 24, 2009

how do you rename your drive from / to C: on linux so it would be recognized by dos

By anon14760 — On Jun 23, 2008

Bev - I don't know how technically savvy you are, but the best thing would be to duplicate your C drive on to the external E drive using a cloning process, then remove the C drive from your computer and install the 325GB inside your computer instead. Now you will boot off the 325GB drive and you can install the smaller "old C" drive in your external enclosure. Once the smaller drive is in the external enclosure, you can wipe it and use it to back up files or whatever. IOW, swap drives.

To clone the old (small) C drive to the external drive, make sure it is cloned and not "imaged" ... an image isn't a bootable drive. It's something that needs to be "restored" before it can be used. You want a virtual clone or the C drive taken to the external drive.

If you do it the old fashioned way by copying C:\ to E:\ make sure you copy all hidden files and folders.

By bev — On Jun 17, 2008

I have just bought and external hard drive 325GB which is great as i have very very little space left on my old C Drive. How do I use my new external E drive as I have been doing with my C drive allowing me to have heaps more space??

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