# The keyword system

Keywords is generaly used to ‘filter’ event for certain group or state.

Keywords can also be used to flag bots with a special tag (like we done with the guard keyword).

The keyword are defined in the ai_service.cfg file.

They exist in three category : npc bot keywords, npc group keywords and npc state keywords.

Each category is limited to 32 keywords.

In most case, you can filter thinks using either explicit name or keyword. Keyword filtering is more restrictive but very faster than name filtering.