An external hard drive is a supplementary data storage device. While it is available in the market, learn how to make it yourself, here.
An external hard drive is, as the name suggests, a storage device that is external to the computer. It's used because it gives extra space for data storage, and moreover it is portable. It is also used as a backup to safeguard any important data.
It is better than CDs and DVDs as it has a much higher storage space and is more durable. You can purchase it at any computer store, but if you have the necessary components, you can assemble it.
The Process
To build this device, one needs a hard drive and an enclosure. If you have the hard drive of your old computer, you can use it. Most external hard drives get the power from a USB cable. If you do not have one, you will need a compatible AC adaptor.
The next step is to purchase an enclosure. An enclosure is a cover which contains all the required plugs for the device such as USB connection and the power plug connection (if required). USB 2.0 is the most commonly used connection.
Open the enclosure as given in the instruction. Set the hard drive to 'master' setting, which is located between the ATA/SATA cable and the molex power connector.
Keep reading the instructions as each device may have its own setting. Connect the molex power connector and ATA/SATA cable to the device.
Fix it to the enclosure with the screws that come with it. Check with the manual if you've followed instructions correctly. If there are any mistakes, make sure they are found before bolting the enclosure shut. Connect the USB cord or power cord (if any) to the internal hard drive and your device is ready!
Getting Started
Turn on your system and connect the device. It will either indicate that the USB device is not recognized or wait for you to go to 'my computer' and then indicate it there. 'Right click' on the sign that says 'Devices with Removable Storage' on the my computer screen and click 'format'.
Make sure that you do not choose the quick format. Formatting will erase all the problem areas that may be on your old hard drive. You can give this drive a name.
Benefits
You can either use it as a backup device for your data or just as an extension of existing memory space. It is always advisable to not use all the memory on your computer's hard drive, as it slows down the system. If you have too much data, use an external storage device.
It is portable and can be connected to any system. So if you have to move around with certain data (presentations, work documents, or even your music and photos) you can carry the drive instead of whole system.