Fan in/Fan-out :-
Fan-in is a measure of the number of process or functions that call some other function or process (say X). Fan-out is the number of functions that are known by function X. A high value for fan-in means that X is tightly coupled to the rest of the design and alters to X will have extensive knock-on effects. A high value for fan-out suggests that the overall difficulty of X may be high because of the difficulty of the control logic required to coordinate the called components.