Hot accretion flows around black holes are classified into cold and hot types. Cold flows, such as the standard thin disk and slim disk, occur at high mass accretion rates and are optically thick. Hot flows, which are the focus of this review, are virially hot and optically thin, occurring at lower mass accretion rates. These flows are characterized by lower radiative efficiency due to energy advection, with efficiency decreasing as mass accretion rate decreases. Hot flows are associated with jets and winds, and their connection to outflows is explored through simulations. They are found in low-luminosity active galactic nuclei and black hole X-ray binaries in hard and quiescent states. The prototype is Sgr A*, a supermassive black hole at the Galactic center. Hot accretion flows can interact with the interstellar medium, influencing galaxy evolution. The review discusses the dynamics, radiation processes, and energetics of hot accretion flows, including models like advection-dominated accretion flow (ADAF), luminous hot accretion flow (LHAF), and their stability. Key parameters such as mass accretion rate, electron heating, and magnetic field strength are analyzed. The review also addresses the radiative efficiency, which can approach that of a standard thin disk at high accretion rates. Observations and simulations suggest that hot flows can produce strong winds and jets, and their role in feedback mechanisms is explored. The review highlights the importance of understanding hot accretion flows for understanding the behavior of black holes in various astrophysical contexts.Hot accretion flows around black holes are classified into cold and hot types. Cold flows, such as the standard thin disk and slim disk, occur at high mass accretion rates and are optically thick. Hot flows, which are the focus of this review, are virially hot and optically thin, occurring at lower mass accretion rates. These flows are characterized by lower radiative efficiency due to energy advection, with efficiency decreasing as mass accretion rate decreases. Hot flows are associated with jets and winds, and their connection to outflows is explored through simulations. They are found in low-luminosity active galactic nuclei and black hole X-ray binaries in hard and quiescent states. The prototype is Sgr A*, a supermassive black hole at the Galactic center. Hot accretion flows can interact with the interstellar medium, influencing galaxy evolution. The review discusses the dynamics, radiation processes, and energetics of hot accretion flows, including models like advection-dominated accretion flow (ADAF), luminous hot accretion flow (LHAF), and their stability. Key parameters such as mass accretion rate, electron heating, and magnetic field strength are analyzed. The review also addresses the radiative efficiency, which can approach that of a standard thin disk at high accretion rates. Observations and simulations suggest that hot flows can produce strong winds and jets, and their role in feedback mechanisms is explored. The review highlights the importance of understanding hot accretion flows for understanding the behavior of black holes in various astrophysical contexts.