Broad objective of this lecture is to presentation on Programming by Contract, here major focus to analysis Pre/Postconditions, Invariants and Assertions. This lecture also discuss on Preconditions, Exceptions in the contract, Assertions, Postconditions and Invariants. Contract is an agreement between classes/objects as well as their clients about how they shall be used. Contract is utilized to assure that objects also have valid state. Finally explain what is postcondition, whose fault is it when a postcondition isn’t met, and what needs to be done?