Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the study of deductively valid inferences or logical truths. It examines how conclusions follow from premises due to the structure of arguments alone, independent of their topic and content. Informal logic is associated with informal fallacies, critical thinking, and argumentation theory. It examines arguments expressed in natural language while formal logic uses formal language. When used as a countable noun, the term "a logic" refers to a logical formal system that articulates a proof system. Logic plays a central role in many fields, such as philosophy, mathematics, computer science, and linguistics.

तर्कशास्त्र म्हणजे प्रमाण अनुमानांचे शास्त्र होय. अनुमान ही विचारांची एक पद्धती आहे. ह्या विचारपद्धतीत चिकित्सापूर्वक निष्कर्षाप्रत येणे अभिप्रेत असते. अनुमानांचे प्रकार, त्यांचे स्वरूप, कोणती अनुमाने प्रमाण ठरतात, प्रमाण ठरण्यासाठी कोणत्या अटींची पूर्तता व्हावी लागते इत्यादी प्रश्नांचा विचार तर्कशास्त्रात होत असतो.