Are you talking about USB hubs? These are devices that plug into a USB port on a PC and turn it into more ports, usually four, but as many as eight.
The only issue I have encountered with them is that they may not provide as much power as some devices need, even if they include their own power bricks. The best thing to do would be to look over reviews (even consumer reviews could be helpful) to see if anyone has had (or not had) power issues with a particular model you are considering.