What is Elon Musk's Neuralink brain chip, now being tested on humans?

A year after being cleared for the test, billionaire Elon Musk's Neuralink has implanted its wireless brain chip in a human for the first time. Musk announced that the patient received the implant on Sunday and "is recovering well". The device is meant to have several applications, from restoring motor functionality within people to enabling a brain-computer interface. There was no independent verification of Musk's claims, and Neuralink did not offer too many details. Musk has touted Neuralink as the future of technology and medicine, but ethical concerns have been raised around the chip and its testing.