Logic

At its most basic logic can be understood as the study of correct reasoning.

Regarding a logicians understanding of this general use Copi explains "Their question is always: Does the conclusion that is reached follow from the premisses used or assumed? If the premisses provide adequate grounds for accepting the conclusion, if asserting the premisses to be true warrants asserting the conclusion to be true also, then the reasoning is correct."

In the context of logic, premises and conclusions are the constituent parts of arguments which make inferrences using propositions: these are sentences which are either true or false.

References:
Symbolic Logic, Fifth Edition by Irving M. Copi

http://www.iep.utm.edu/prop-log/

https://plato.stanford.edu/entries/logic-classical/

http://www.logicmatters.net/tyl/