A human interface device (HID) is a type of computer device that
interacts directly with and takes input from humans. The term "HID"
most commonly used to refer to the USB-HID specification, but other
devices (such as, but not strictly limited to, Bluetooth) are
designed using HID specification (this involves certain keyboards,
mice, tablets, etc). This option adds the HID bus to the kernel,
together with generic HID layer code. The HID devices are added and
removed from the HID bus by the transport-layer drivers, such as
usbhid (USB_HID) and hidp (BT_HIDP).

For docs and specs, see http://www.usb.org/developers/hidpage/

If unsure, say Y.

source code:

drivers/hid/