They can use many different interfaces depending on the drive, although most use USB. Although the four main are:
7-pin connector
the main advantage of an external drive is it being portable. it is not necessary to unplug unless you want to connect it to another computer.
The main function of the Ethernet external hard drive is to connect the internet between the modem and the computer. To be able to connect internet, you need an Ethernet cable.
Connect the hard-drive to a computer via the USB port. On the 'host' computer - click on the 'My computer' icon Select the external hard drive from the list of available devices (probably 'E' drive)
Connect an external hard drive to your computer and copy over important files.
Connect the drive to your computer, open Windows Explorer, locate the drive. Right click -> properties.
Simply connect your external hard disk to your computer. Then select the songs you want to play later, copy them and paste to your computer hard drive. And after disconnecting your external hard disk you can now play the selected songs from your computer hard drive.
though an External HardDrive with usb interface
You will need to connect it to a computer to read what is on the external drive. As a precaution, always scan external storage devices with anti-virus programs before opening any content on a drive.
Connect the drive to a computer, use the device manager or system profiler (mac) to try to determine the model of the drive. From that, you can google the model and find out the capacity, interface style (IDE, SCSI, SATA), form-factor (regular or notebook), etc. Then open the external drive enclosure and look at the drive - it's usually just a regular drive (or tiny notebook drive). It will also have whatever adapters are needed by the enclosure to supply power, a data interface, and maybe lights or fans. You can remove the drive from the enclosure and put it in a computer. You may need a different mounting kit if the drive is too small, or an interface adapter if your computer doesn't have the same interface.
Yes, you can using USB.
External Hard Drives are generally connected to USB ports or FireWire ports.