Take the 2-minute tour ×  With my little knowledge, I know this:
Dark Matter  The center of a galaxy controls/attracts its
objects (stars, planets, comets etc.) towards itself because of
gravity. But the mass of the center of this galaxy appears to be
less than what it should take to attract all objects of the
galaxy. Hence Dark Matter is there, which makes this attraction
or controlling possible.  Dark Energy  This is the force which
is pulling galaxies away from each other, and hence making the
universe expand. If we don't have this hypothetical force, we
cannot explain why distances between galaxies are increasing.
Please let me know how far I am from the actual
meaning/definition of these terms? And how can I explain these
to a layman, who has no or very little knowledge about
astronomy?   P.S.: I have read this question here, which is
excellent but I could not get an idea of how to explain to a
layman.  share|improve this question Basically the layman's
version of MBR's answer for dark matter in the l