DANGEROUS, a word I should mention. I am comfortable to work with electronics and below 12V, but working with 110V/220V is another ball game.
Having said that, electricity from main voltage is what we all use. The lucky part is that there is professional doing the job for us, so that we enjoy the service of electricity brought to.
With IoT in mind, having your own energy meter can be insightful into your energy use. There are a few options to monitor and display your energy flow besides the one from the provider. In this tutorial, we will explore a Peacefair PZEM-004T v3 model that is ready for IoT hobbyist. PZEM-004T built in one serial port (TX/RX) that can be write and read by an Arduino or ESP8266/32. Alternatively, energy meters from Peacefair are avaiable in other PZEM 0-100A variants.