If your computer is more than a couple of years old, SDHC camera memory cards might not be readable in the computer's SD card slot (if it even has one) so you need a little device like this. Connecting your camera to your computer by cable is dreadfully slow and clumsy and is for emergencies only. With this card reader, you just take the SDHC card out of the camera, pop it in the slot, and plug the reader into a USB port. Then it behaves like a removable disk, and shows up in Computer on a PC or Finder on a Mac. You can copy photos and movies into any folders on the computer, and also delete unwanted shots from the memory card.
At a value price and with quick delivery included, this was an essential to go with my new camera.