Late binding

Late binding, or dynamic binding, is a computer programming mechanism in which the method being called upon an object or the function being called with arguments is looked up by name at runtime.

With early binding, or static binding, in an object-oriented language, the compilation phase fixes all types of variables and expressions. This is usually stored in the compiled program as an offset in a virtual method table ("v-table") and is very efficient. With late binding the compiler does not have enough information to verify the method even exists, let alone bind to its particular slot on the v-table. Instead the method is looked up by name at runtime.