Help with a smart TV

Hi! I was hoping someone here could explain what a smart TV is. Right now we are using my computer as our TV but I want to move my computer back into my office and get TV for the living room. We would basically just need a TV that streams Netflix, plays DVD with my external smartdrive, and play the Xbox.  We have a great wifi connection and a Netflix subscription. What's my next step? What's a roku? I basically just find a zillion bad reviews about it online haha   Someone help me out! :)