This review discusses the halo-based description of nonlinear gravitational clustering, which associates all mass with virialized dark matter halos. The model estimates the statistical properties of large-scale density and velocity fields by modeling the number and spatial distribution of halos and the distribution of dark matter within each halo. The authors first describe the model and demonstrate its accuracy by comparing predictions with numerical simulations. They then present several astrophysical applications of the halo model, including models of galaxy distribution, nonlinear velocity and momentum fields, weak gravitational lensing, and secondary contributions to temperature fluctuations in the cosmic microwave background. The review covers background materials, dark matter halo properties, the halo model, and its applications to various physical quantities. It also discusses the limitations of perturbation theory and introduces hyper-extended perturbation theory (HEPT) as a more accurate description of highly nonlinear regimes.This review discusses the halo-based description of nonlinear gravitational clustering, which associates all mass with virialized dark matter halos. The model estimates the statistical properties of large-scale density and velocity fields by modeling the number and spatial distribution of halos and the distribution of dark matter within each halo. The authors first describe the model and demonstrate its accuracy by comparing predictions with numerical simulations. They then present several astrophysical applications of the halo model, including models of galaxy distribution, nonlinear velocity and momentum fields, weak gravitational lensing, and secondary contributions to temperature fluctuations in the cosmic microwave background. The review covers background materials, dark matter halo properties, the halo model, and its applications to various physical quantities. It also discusses the limitations of perturbation theory and introduces hyper-extended perturbation theory (HEPT) as a more accurate description of highly nonlinear regimes.