A portable storage device that delivers content to smartphones, tablets and laptops. It functions like a USB drive with internal storage and may have additional plug-in storage via an SD Card. Although it generally cables to a computer's USB port to download documents, images and videos, users employ the vendor's mobile app to retrieve the data from the hub via Wi-Fi. This type of device is more a "media server" than a hub, because it stores the content rather than streaming it from the Internet. Some units also function as a portable USB charging source while others may have an Ethernet port to create a Wi-Fi hotspot in hotels and venues that only have wired Internet connections. See digital media hub and digital media server.