Final answer:
IR connectivity on mobile devices refers to Infrared connectivity, similar to that used by TV remotes, requiring direct line of sight for signal transmission. Bluetooth is an alternative that doesn't require line of sight.
Step-by-step explanation:
On many mobile devices, especially Android devices, the term "IR" connectivity stands for Infrared connectivity. This technology is akin to the familiar handheld TV remotes that transmit their commands via an infrared beam. These beams require a direct line of sight between the remote's infrared emitter and the television's infrared detector for the signal to be received. In contrast, some modern remotes use Bluetooth technology, enabling the remote to function without the need for direct line of sight, which can reduce the inconvenience of the controller not working if something is blocking the path of the infrared signal.