External Hard Drive
An external hard drive is a portable device used to store data. They are just like the hard drives already in a computer except, as the name implies, they are external. They can be disconnected and reconnected at will. Typical external hard drive sizes range from 500GB to 3TB with more expensive ones ranging from 3TB to 4TB. External hard drives are useful for backing up data and for the use of keeping data in two locations in case of unforeseen computer crashes.
Using your External Hard Drive
For Mac users, it is very strongly recommended that you do not backup your data using Time Machine. If you purchase an external hard drive and plug it into your Mac, this window will pop up. You will need to select "Don't Use"
The next step will be properly formatting your external hard drive before backing up your data. To format your hard drive, within the spotlight search option in the top right corner of your desktop, type in "Disk Utility" and select it from the menu.
You will then need to select the name of your external hard drive from the left hand column. It is critical you do not select the hard drive for your laptop which will be the first option from the column. Once you have the external hard drive selected, as highlighted in blue in the image, select the "Erase" tab right after the "First Aid" tab, and select the "ExFAT" option within the "Format" list. You can rename the external hard drive to whatever you like within the "Name" text box. At this point, you should double check that you have the external hard drive highlighted and not the hard drive for your laptop. If you are positive that the external hard drive is highlighted and selected, you can select the "Erase..." option in the bottom right corner of the window to format your external hard drive.
If done correctly, you will see your hard drive appear on your desktop again and it will be renamed to whatever you entered in the "Name" text box. You can now drag and drop your data onto your renamed external hard drive.