 Negation is in the first place a phenomenon of semantic opposition. As such, negation relates an expression \(e\) to another expression with a meaning that is in some way opposed to the meaning of \(e\). This relation may be realized syntactically and pragmatically in various ways. Moreover, there are different kinds of semantic opposition.  Section 1  is concerned mainly with negation and opposition in natural language, both from a historical and a systematic perspective.  Section 2  focuses on negation as a unary connective from the point of view of philosophical logic. The history of negation is comprehensively studied and surveyed in Horn 1989 and Speranza and Horn 2012.