The criteria used by the Java compiler to determine which method within a class to execute when a method call is made. The signature includes the scope, return type, method name, and parameter types for the method, but not the exceptions thrown by the method. Overriding methods must have the same signature as the methods they override; overloaded methods must have the same return type and method name, but not the same parameter types as the methods they overload.

a combination of its argument types and return values

an abstract concept - not something you can type in anywhere

a collection of information about the method, as in a C prototype or a forward function declaration in other languages