1. User interface apparatus for uce with a machine which can receive a number of user instructions to reach one of a plurality of possible machine states, wherein said user instructions can be input to said machine using at least natural language as a mode of input, the user interface apparatus comprising: status means for obtaining a current state of said machine; generating means responsive to the obtained current state of said machine to generate information to inform a user of a natural language instruction which can be input to said machine to achieve the current state of said machine; and output means for outputting the generated information to the user.