  The modified Gauss-Bonnet gravity can be motivated by a number of physical
reasons, including: the uniqueness of a gravitational Lagrangian in four and
higher dimensions and the leading order $\alpha^\prime$ corrections in
superstring theory. Such an effective theory of scalar-tensor gravity has been
modeled in the recent past to explain both the initial cosmological singularity
problem and the observationally supported cosmological perturbations. Here I
present an overview of the recent developments in the use of modified
Gauss-Bonnet gravity to explain current observations, touching on key
cosmological and astrophysical constraints applicable to theories of
scalar-tensor gravity. The Gauss-Bonnet type modification of Einstein's theory
admits nonsingular solutions for a wide range of scalar-curvature couplings. It
also provides plausible explanation to some outstanding cosmological
conundrums, including: the transition from matter dominance to dark energy and
the late time cosmic acceleration. The focus is placed here to constrain such
an effective theory of gravity against the recent cosmological and
astrophysical observations.
