What is ln 0?

The natural logarithm of 0, denoted as ln(0), is undefined. This is because the natural logarithm function is only defined for positive real numbers, and 0 is not a positive real number. In mathematical terms, the natural logarithm function approaches negative infinity as the input approaches 0 from the right, but it is not defined at exactly 0. Therefore, ln(0) is considered undefined in mathematics.