A looking inward; specifically, the act or process of self-examination, or inspection of one's own thoughts and feelings; the cognition which the mind has of its own acts and states
Systematic observation of places and people by visual, aural, electronic, photographic or other means.
Continuous monitoring of disease occurrence for example.
Close observation of an individual or group; person or persons under suspicion.
In criminal law, an investigation process by which police gather evidence about crimes, or suspected crime, through continued observation of persons or places.