• organize and reduce dependencies between classes

Client

-- A method m is a client of C if m calls a method of C

Supplier

-- If m is a client of C then C is a supplier of m

Acquaintance

-- C is an acquaintance of m if C is a supplier of m but not (the type of) an argument of m or (of) an instance variable of the object of m

• C is a preferred acquaintance of m if an object of C is created in m or C is the type of a global variable
• C is a preferred supplier of m if C is a supplier and C is (the type of) an instance variable, an argument or a preferred acquaintance