How do headphones, toys, gadgets and other devices talk to each other without any wires? Many of them connect with Bluetooth. It’s a technology that allows different devices to communicate wirelessly.

Landing a plane on a small flight deck is far harder than on a large runway—and requires a much larger support crew.

In the spring and summer of 1991, Torvalds hacked on a simple Unix‑like kernel for his 386 PC. He wanted to learn about operating systems, dial into the local Usenet server, and build a more capable ...