Modern Cosmology is a mature branch of science based on the Big Bang theory and the Inflationary Paradigm. It allows us to define a Standard Model of Cosmology with precise parameters, determined within a few percent. This precision era is made possible by experimental developments in various fields, including supernova observations, microwave background anisotropies, and the distribution of matter in galaxies and clusters. The Big Bang theory explains the universe's evolution from the first fraction of a second to its current age of about 13.6 billion years. It is based on general relativity and three observational facts: the universe's expansion, the abundance of light elements, and the cosmic microwave background (CMB). The CMB, discovered in 1965, is the afterglow of the Big Bang and provides information about the early universe. The universe is described by the Friedmann-Robertson-Walker (FRW) metric, characterized by a scale factor $ a(t) $ and spatial curvature $ K $. The universe can be open, flat, or closed, depending on the value of $ K $. The Friedmann equations describe the dynamics of the universe, including the expansion rate and the influence of matter and energy content. The matter and energy content of the universe is described by different types of fluids: radiation, matter, and vacuum energy. The cosmological parameters include the Hubble parameter $ H_0 $, the critical density $ \rho_c $, the density parameters $ \Omega_M $, $ \Omega_\Lambda $, and $ \Omega_K $, and the deceleration parameter $ q_0 $. These parameters help determine the universe's expansion history and its current state. The accelerating universe is a key observation, indicating the presence of a repulsive force, likely dark energy. The deceleration parameter $ q_0 $ has been measured, showing that the universe is currently accelerating. This has led to the conclusion that the universe is dominated by dark energy, with $ \Omega_\Lambda \approx 0.7 $. The $ (\Omega_M, \Omega_\Lambda) $ plane is used to plot observations and determine the universe's parameters. The data from supernovae and other observations have shown that the universe is spatially flat and accelerating, with $ \Omega_M \approx 0.3 $ and $ \Omega_\Lambda \approx 0.7 $. Dark matter is inferred from observations such as galaxy rotation curves, the baryon fraction in clusters, and weak gravitational lensing. These observations suggest that dark matter is a significant component of the universe, with a mass much larger than the visible matter. The formation of large-scale structure in the universe is explained by small primordial inhomogeneities that grew through gravitational instability. The power spectrum of the matter distribution provides insights into the universe's structure and evolution. The CMB anisotropies and the power spectrumModern Cosmology is a mature branch of science based on the Big Bang theory and the Inflationary Paradigm. It allows us to define a Standard Model of Cosmology with precise parameters, determined within a few percent. This precision era is made possible by experimental developments in various fields, including supernova observations, microwave background anisotropies, and the distribution of matter in galaxies and clusters. The Big Bang theory explains the universe's evolution from the first fraction of a second to its current age of about 13.6 billion years. It is based on general relativity and three observational facts: the universe's expansion, the abundance of light elements, and the cosmic microwave background (CMB). The CMB, discovered in 1965, is the afterglow of the Big Bang and provides information about the early universe. The universe is described by the Friedmann-Robertson-Walker (FRW) metric, characterized by a scale factor $ a(t) $ and spatial curvature $ K $. The universe can be open, flat, or closed, depending on the value of $ K $. The Friedmann equations describe the dynamics of the universe, including the expansion rate and the influence of matter and energy content. The matter and energy content of the universe is described by different types of fluids: radiation, matter, and vacuum energy. The cosmological parameters include the Hubble parameter $ H_0 $, the critical density $ \rho_c $, the density parameters $ \Omega_M $, $ \Omega_\Lambda $, and $ \Omega_K $, and the deceleration parameter $ q_0 $. These parameters help determine the universe's expansion history and its current state. The accelerating universe is a key observation, indicating the presence of a repulsive force, likely dark energy. The deceleration parameter $ q_0 $ has been measured, showing that the universe is currently accelerating. This has led to the conclusion that the universe is dominated by dark energy, with $ \Omega_\Lambda \approx 0.7 $. The $ (\Omega_M, \Omega_\Lambda) $ plane is used to plot observations and determine the universe's parameters. The data from supernovae and other observations have shown that the universe is spatially flat and accelerating, with $ \Omega_M \approx 0.3 $ and $ \Omega_\Lambda \approx 0.7 $. Dark matter is inferred from observations such as galaxy rotation curves, the baryon fraction in clusters, and weak gravitational lensing. These observations suggest that dark matter is a significant component of the universe, with a mass much larger than the visible matter. The formation of large-scale structure in the universe is explained by small primordial inhomogeneities that grew through gravitational instability. The power spectrum of the matter distribution provides insights into the universe's structure and evolution. The CMB anisotropies and the power spectrum