External HDDs are usually connected to a computer via a USB cable.
If you do run out of data then it is more than possible for you to delete data before you go on to store more. The storage of the HDD will ultimately determine how much data you can store at any one time. The external HDD you choose will largely depend on the reason for your purchase, the amount of data that you need to store and even the speed at which you need to store that data. Some of these include the USB 3.0, the USB 2.0, wireless devices and even the Thunderbolt as well. External hard disc drives (HDDs) come in many different variations.
