  Let $f$ and $g$ be analytic on the unit disc $\mathbb{D}$. The integral
operator $T_g$ is defined by $ T_g f(z) = \int_0^z f(t)g'(t)\,dt$, $z \in
\mathbb{D}$. The problem considered is characterizing those symbols $g$ for
which $T_g$ acting on $H^\infty$, the space of bounded analytic functions on
$\mathbb{D}$, is bounded or compact. When the symbol is univalent, these become
questions in univalent function theory. The corresponding problems for the
companion operator, $ S_g f(z)= \int_0^z f'(t)g(t)\, dt$, acting on $H^\infty$
are also studied.
