What is a USB Mass Storage Device?

USB mass storage device class (English: USB mass storage device class, also known as USB MSC or UMS) is a protocol that allows a USB interface device to be connected to a host computing device in order to transfer files between the two. To the host computing device, the USB device looks like a removable hard drive, allowing drag-and-drop file transfers. It is actually a summary of many communication protocols adopted by the USB Implementers Forum. This standard provides the interface of many devices. Including mobile hard drives, flash drives, mobile optical drives, card readers, digital cameras, digital music players, PDAs, and cell phones.