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 compiles into kernel the generic
HID layer code (parser, usages, etc.), which can then be used by
transport-specific HID implementation (like USB or Bluetooth).

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

If unsure, say Y.

source code:

drivers/hid/