Switches are a big seller of mine and useful in many situations. They are the simplest networking device there is -- no setup, no configuration, just plug and go.This is used when you have a device that does the routing (a router than gives IP addresses) and you don't have enough ports for all of your wired devices. You can also use it in a situation where you have one computer jack in an office or room, but more than one device.I used a network cable to plug from the router to the new switch and plugged in my devices into the switch and they all instantly worked. If you are expecting a speed increase, make sure that your computer has a gigabit ethernet port -- most business computers have had that for quite a few years now and I'm not sure what they are putting in home computers.I also have installed more than a dozen of this exact switch (beginning in December 2011) in many locations without one failure so far. Before I tried TP-Link, I bought a Netgear and it failed at 13 months. I bought a TrendNET and it failed after one week.This is what I buy now, and I would recommend for you. 

Question: What happens to the ports if you plug it in?
Answer: just plug and go