The article reviews the current understanding of hot accretion flows around black holes, which are characterized by virial temperatures and optically thin gas. These flows occur at lower mass accretion rates compared to cold accretion flows and are described by models such as advection-dominated accretion flows (ADAFs) and luminous hot accretion flows (LHAFs). The radiative efficiency of hot accretion flows is generally lower than that of standard thin disks due to energy advection, but it can increase with increasing mass accretion rate. The article discusses the stability and relationship to other accretion solutions, numerical simulations, and applications to various black hole systems, including the Galactic Center black hole Sgr A* and low-luminosity active galactic nuclei. It also explores the link between hot accretion flows and outflows, such as jets and winds, and their potential role in galaxy feedback mechanisms. The radiative processes, spectrum, and radiative efficiency of hot accretion flows are analyzed, and the energy equation is discussed in detail, including the roles of viscous heating, compressional heating, energy advection, Coulomb energy transfer, and radiative cooling. The article concludes with a discussion of the critical mass accretion rates that separate different regimes of hot accretion flows and their implications for the observed properties of black hole sources.The article reviews the current understanding of hot accretion flows around black holes, which are characterized by virial temperatures and optically thin gas. These flows occur at lower mass accretion rates compared to cold accretion flows and are described by models such as advection-dominated accretion flows (ADAFs) and luminous hot accretion flows (LHAFs). The radiative efficiency of hot accretion flows is generally lower than that of standard thin disks due to energy advection, but it can increase with increasing mass accretion rate. The article discusses the stability and relationship to other accretion solutions, numerical simulations, and applications to various black hole systems, including the Galactic Center black hole Sgr A* and low-luminosity active galactic nuclei. It also explores the link between hot accretion flows and outflows, such as jets and winds, and their potential role in galaxy feedback mechanisms. The radiative processes, spectrum, and radiative efficiency of hot accretion flows are analyzed, and the energy equation is discussed in detail, including the roles of viscous heating, compressional heating, energy advection, Coulomb energy transfer, and radiative cooling. The article concludes with a discussion of the critical mass accretion rates that separate different regimes of hot accretion flows and their implications for the observed properties of black hole sources.