Logarithmic Equation:An equation that involves a logarithm with a variable argument, typically taking forms like $\log_b(x) = y$.
Base:The constant value that is raised to a power in an exponential expression, such as $a$ in $a^x$.
$e$ (Euler's Number): $e$ is an irrational and transcendental number approximately equal to 2.71828, commonly used as the base for natural logarithms.