Q. What is Common coupling?

Common coupling: With general coupling module A and module B have shared data. Global data areas are usually found in programming languages. Formulating a change to the common data means tracing back to all the modules which access that data to evaluate the effect of change. With common coupling it is able to be difficult to determine which module is responsible for having set a variable to a particular value. Fig. below demonstrates how common coupling works

Content coupling: Content coupling take places when module A changes data of module B or when control is passed.