算术溢出（arithmetic overflow）或简称为溢出（overflow）指的是：

加法器是中央处理器算术逻辑单元中的核心之一。当长度为n位的两个二进制数经过加减法器运算，得到的长度为n位的结果不是正确值时，我们说发生溢出。

The term arithmetic overflow or simply overflow has the following meanings.

Most computers distinguish between two kinds of overflow conditions. A carry occurs when the result of an addition or subtraction, considering the operands and result as unsigned numbers, does not fit in the result. Therefore, it is useful to check the carry flag after adding or subtracting numbers that are interpreted as unsigned values. An overflow proper occurs when the result does not have the sign that one would predict from the signs of the operands (e.g. a negative result when adding two positive numbers). Therefore, it is useful to check the overflow flag after adding or subtracting numbers that are represented in two's complement form (i.e. they are considered signed numbers).