A prototype chain is analogous to the super/sub-class inheritance mechanisms in an object-oriented environment. It is not quite the same, however, because the inheritance takes place at the object level and there are no true classes to instantiate. Instead you clone existing objects.
ECMA 262 edition 2 - section - 4.2.1
ECMA 262 edition 2 - section - 8.6.2
ECMA 262 edition 3 - section - 4.2.1
ECMA 262 edition 3 - section - 8.6.2