Anything described and held to be true; any
datum that, within the domain of an observer's powers, cannot be ignored, modified or explained away and must therefore be included in that observer's
construct or
model . Facts are contrasted with statements that are untrue or surmised, with untested hypotheses, beliefs and fantasies, and with phenomena that are subject to change, e.g., with a
self-fulfilling hypothesis. (
Krippendorff )
