  In this paper, we investigate the caustic point developed by outgoing null
hypersurfaces and the behavior of null curves. We analyze three cases: Future,
past, and zero caustic point terminology for outgoing null hypersurfaces in the
marginally bound Lemaitre-Tolman-Bondi (LTB) metric for homogenous and
inhomogeneous cases defined in the present work. We show the criteria to form
local and globally visible singularity in terms of the tangent on the apparent
horizon curve.
