Extensibility of XWiki

Dear XWiki Community I am completely new to XWiki but so far I think, it could be a ideal starting point for realizing a personal documentation system. However, I would need to extend XWiki for new custom tags which would allow me structuring my contents in a special way. Can this easily be done with XWiki? Are plugins the "way to go"? Can limitations for XWiki's extensibility already be pointed out? Thanks a lot! ma/esch