The LCD and digitizer remains.

The Touch ID function will ONLY work with your phone's original home button assembly, so you'll need to transfer the home button assembly from your old display assembly to your new display assembly to retain Touch ID.

After reassembly, clean the touchscreen surface with an alcohol wipe prior to turning the iPhone back on. The alcohol helps dissipate any lingering static electricity, which can cause problems with the display.

After reassembly, connect the iPhone to an AC power source before turning it on for the first time. Once the iPhone has booted up successfully, you can disconnect the AC power.