Exponential Growth:A process that increases quantity over time at a rate proportional to its current value, often expressed as $N(t) = N_0 e^{kt}$.
Half-life:The period it takes for a substance undergoing exponential decay to reduce to half its initial amount.
\ln (Natural Logarithm): \ln(x)$ represents the natural logarithm of x and is the inverse function of $e^x$ (exponential function).