1. An information-processing apparatus comprising: detection means for detecting conditions surrounding the user and generating sensing data revealing said conditions surrounding said user; recognition means for recognizing said conditions surrounding said user on the basis of said sensing data; and meta-information generation means for generating meta information in the form of structured information to be used for detecting a change in said conditions surrounding said user on the basis of one or more pieces of said sensing data and recognition information showing a recognition result produced by said condition recognition means.