This text is for academics, postgraduates and upper-level students who want to know more about formal logic. The text assumes some elementary knowledge of formal logic. It covers the semantics and axiomatics of modern classical formal logic, as well as proofs of soundness, completeness, and both of Gödel's theorems. There is also a discussion of the pictorial semantics of various logic diagrams: Euler, Carroll, and Venn diagrams, Karnaugh maps, and switching circuits. Lastly, the book covers the reliability of classical formal logic for the evaluation of everyday argumentation, and Nether Logic, the logic of the transmission of falsehood.