An external hard drive is a device, exactly the same size as that of a book, that helps you save all of your apps and files. If you’re familiar with using the USB flash drive, external hard drives are just like them. But they are bigger in size with more storage capacity.
The key difference between a hard drive (HD) and an external hard drive (external HD) is that the external HD is portable and easy to carry. You can disconnect it at any time and take it with you, at your ease. No need to worry because you’ll not lose data inside.