Reset SMC in macOS

How to Reset the System Management Controller (SMC)

Shut the laptop down
Plug the power cable in
Make sure the laptop is powered off
At the same time press SHFT+CTRL+OPT+power and hold for 10 seconds
Let go and turn the laptop on normally

Why do we do this?

The SMC is the system management controller. Resetting the SMC is a similar operation to resetting the NVRAM. Apple recommends resetting it to fix issues with power, battery, fans, and other features.