Funny ketchup bottle December 8, 2008

Visibility of system status: the system should always keep users informed about what is going on, through appropriate feedback within reasonable time.

Match between system and the real world: the system should speak the users’ language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order.

(From Nielsen’s usability heuristics).