  We present astrophysical applications of the recently popular halo model to
describe large scale structure clustering. We formulate the power spectrum,
bispectrum and trispectrum of dark matter density field in terms of
correlations within and between dark matter halos. The halo approach uses
results from numerical simulations and involves a profile for dark matter, a
mass function for halos, and a description of halo biasing with respect to the
linear density field. This technique can easily be extended to describe
clustering of any property of the large scale structure, such as galaxies,
baryons and pressure, provided that one formulate the relationship between such
properties and dark matter. In detail, we discuss applications of the halo
model for several observational probes of the local universe involving weak
gravitational lensing, thermal Sunyaev-Zel'dovich (SZ) effect and the kinetic
SZ effect. We also propose a new cosmological test using the redshift evolution
of the angular power spectrum of halos and using a calibrated linear power
spectrum, which acts as an effective standard ruler (Summary).
