How does overflow affect the behavior of two's complement numbers, specifically in making them act as negative values?

Overflow in two's complement numbers occurs when the result of an arithmetic operation exceeds the range that can be represented by the given number of bits. This can cause the number to "wrap around" and appear as a negative value. For example, if adding two positive numbers results in a value greater than the maximum positive value that can be represented, the number will overflow and be interpreted as a negative value.