Definition:Logic

Logic is the study of the structure of statements and their truth values, divorced from their conceptual content.

Logic can be considered as the rickety gangplank between the ship of language and the solid ground of mathematics. In this context, "language" is often called natural language.

Branches of Logic
There are several branches of logic, for example:

Aristotelian logic, in which all statements have a truth value that is either true or false.

Multi-value logic, in which it is admissible for a statement to have a truth value other than those two values.

Symbolic logic, in which the logical form of statements is analysed by using symbols as tools.

Mathematical logic, in which the foundations of the assumptions upon which rest mathematics itself are investigated and made rigorous.

Propositional logic, a sub-branch of symbolic logic in which the truth values of statements is investigated and analysed.

Predicate logic, an extension of propositional logic in which the internal structure of statements is analysed.

Modal logic, in which truth values are more complex than being merely "true" or "false", and which distinguishes between different "modes" of truth.