Why is the integral of $dx$ equal to $x$=?iso-8859-1?Q?=3F_=96_math.stackexchange.com?=

Why is the integral of $dx$ equal to $x$? – math.stackexchange.com

Please give a thorough explanation, not just "$dx$ is the derivative of
$x$, so the antiderivative of $dx$ is $x$, duh".