These fighting systems fall into three categories, speed-based, descriptive, and turn-based. Of these, the former is such that the involved parties seek to outmatch one another via superior typing speed and stratagem, and thus is usually left for websites or programs that support an instant messenger or chats. The latter has no emphasis on typing speed, but focuses wholly on strategy, and are thus usually based on forums and message boards. Both systems are further divided into explicit and implicit subsets (also called open and closed), which refer to whether the outcome of an attack is stated by the attacker or assumed to have happened in the flow of battle.