Join Date:Joined: Dec 2010
When you have a USB connection, one end acts as the "host" and the other acts as the "device." Typically standard "computers" (desktops, laptops, etc) act as hosts and what you plug in acts as a device. However, some devices that support USB On The Go (OTG) can switch between host mode and device mode.
When a device is in host mode, if it has the appropriate drivers, you can do things like plug in keyboards, mice, thumb drives, cameras, etc and control them from the host mode device.