The Cosmic Microwave Background is isotropic to a high degree and hence early universe was rather homogeneous at the time CMB was formed. Low-level anisotropy in CMB implies small perturbations of matter and geometry. In cosmological perturbation theory, the background space-time is Friedmann-Robertson-Walker metric which is invariant under spatial rotation and spatial translation. It is possible to divide the perturbations to scaler, vector and tensor parts. Standard Cosmological Model describe universe as a perfect fluid components and its energy-momentum tensor will be a perfect barotropic energy-momentum tensor. In this thesis evolution of perturbation in different era will be studied and scaler perturbations will be solved. Kodama-Sasaki equations will be solved in terms of scale factor normalized to equality scale factor. The Boltzmann perturbed equation are derived for interacting fluid components. Angular power spectrum will be a theoretical tool to study the CMB correlations which affected by different fluid component quantities. Angular power spectrum for Sachs-Wolfe effect in matter dominated era and other fluid component will be derived and described via different plots.
