The IEEE 754 standard defines the behavior of a numeric environment in such a way that the computation should generate the same result across any compliant platforms.
It specifies the exact format for the storage and manipulation of the values. It also specifies bounding ranges for exponents and mantissas.
The standards describes how and when rounding should occur and the direction in which rounding takes place. Exceptions are also described and this determines how the NaN value is generated and propagated through expressions.