  We discuss the way non-perturbative quantization of cosmological spacetimes
in loop quantum cosmology provides insights on the physics of Planck scale and
the resolution of big bang singularity. In recent years, rigorous examination
of mathematical and physical aspects of the quantum theory has led to a
consistent quantization which is consistent and physically viable and some
early ideas have been ruled out. The latter include so called `physical
effects' originating from modifications to inverse scale factors in the flat
models. The singularity resolution is understood to originate from the
non-local nature of curvature in the quantum theory and the underlying polymer
representation. Using an exactly solvable model various insights have been
gained. The model predicts a generic occurrence of bounce for states in the
physical Hilbert space and a supremum for the spectrum of the energy density
operator. It also provides answers to the growth of fluctuations, showing that
semi-classicality is preserved to an amazing degree across the bounce.
