The HID protocol is used by USB keyboards, and HID uses the USB "interrupt"transfer type, which allocates 1 packet per a configurable number of USBframes. Each USB frame is 1ms, and the Teensyduino USB keyboard coderequests the interval to be every frame. If the operating system honorsthis request, bandwidth is available for 1000 packets per second.
Your PC orMac will detect a new keyboard. Then your program can send keystrokeswhich your computer will recognize as coming from a standard USB keyboard.