Lifi is short form of light fidelity. Faster than Wi-Fi and uses special bulbs as access point. It is a developing technology and I've never seen it in reality though I wrote an article on it in steemit website

Pros: The little I know is thats its super fast up to 1gig/sec, and it uses bulbs to transmits its waves.
cons: it cannot pass through walls successfully since light can't pass through walls.
Some advanced countries are already but before such tech gets down here would still be in some years to come though