a dedicated server is something that serves as the host for a game, and all the players are in turn clients. it solves problems that are very common on the consoles that provide online gaming through a local host system. with a dedicated server, the only thing that determines your quality of play (ping time) is the distance you live from the server, so your gameplay cannot be impeded upon by say, a local host with a terrible internet connection due to family members browsing the web. It also eliminates the ability for people to lag switch, as well as to lock a room in order to boost.