Smart displays are the tech world's latest fetish. They're smart speakers with a voice assistant like Google Assistant or Amazon Alexa--and a tablet-sized screen on the front to show the weather, album art, TV shows, video calls, and other (mostly) useful stuff. With Facebook and Google jumping into the fray with their own displays, it's a good time to step back and examine the LCD-filled terrain. Below are most of major smart displays on the market and what they're good for.