What is fan-in and fan-out, and what attribute do they measure?
Answer: Fan-in is a measure of number of information flow into a module or component. Fan-out is the number of information flow out of a module.
An example of fan-in for module-x would be the number of modules that call module-x and for fan-out of module-x would be the number of modules that are called by module-x. Thus fan-in and fan-out measure the coupling attribute among modules.