IFTTT (If This Then That) is a powerful free to use tool that allows you to create custom commands between various services. For example if my WeMo smart light switch and Google Home are both connected to IFTTT I can then tell Google Home to turn my light switch on or off.
IFTTT isn’t just limited to smart home products, for example if someone likes a Facebook post then you can write a phrase to a Google Doc document. Sure that makes no sense but the idea is that you’re free to do whatever you want. To understand it better and how to use it be sure to watch the video below.