The Local Group (LG) dwarf galaxies offer a unique window into the properties of the most common type of galaxy in the Universe. This review updates the census of LG dwarfs based on recent distance and radial velocity determinations and discusses their detailed properties, including photometric parameters, interstellar medium (ISM) content, heavy-element abundances, star-formation histories, kinematics, and interactions with other galaxies. The review also presents extensive observational data in tables to summarize what is known and unknown about these nearby dwarfs. The LG dwarfs are particularly important for studying dark matter, galaxy evolution, and the relationship between stellar populations and the ISM. The review highlights the importance of these galaxies in understanding the dark-matter problem and the dynamics of galaxy interactions. The current census of likely LG dwarfs is estimated to be 38 ± 6, with many more yet to be discovered. The structure of the Local Group is analyzed, revealing subgroups and the distribution of galaxies. The optical photometric and structural properties of LG dwarfs are discussed, showing variations in their characteristics. The ISM of LG dwarfs is examined, revealing differences in HI content, dust, molecular gas, and HII regions. The review also addresses the 'ISM crisis' in dSph galaxies, where some have no detectable gas despite having young stars. The study of LG dwarfs provides insights into galaxy evolution, dark matter, and the role of interactions in shaping galaxy structures. The review concludes that these galaxies remain a key area of study for understanding the evolution of galaxies in the Universe.The Local Group (LG) dwarf galaxies offer a unique window into the properties of the most common type of galaxy in the Universe. This review updates the census of LG dwarfs based on recent distance and radial velocity determinations and discusses their detailed properties, including photometric parameters, interstellar medium (ISM) content, heavy-element abundances, star-formation histories, kinematics, and interactions with other galaxies. The review also presents extensive observational data in tables to summarize what is known and unknown about these nearby dwarfs. The LG dwarfs are particularly important for studying dark matter, galaxy evolution, and the relationship between stellar populations and the ISM. The review highlights the importance of these galaxies in understanding the dark-matter problem and the dynamics of galaxy interactions. The current census of likely LG dwarfs is estimated to be 38 ± 6, with many more yet to be discovered. The structure of the Local Group is analyzed, revealing subgroups and the distribution of galaxies. The optical photometric and structural properties of LG dwarfs are discussed, showing variations in their characteristics. The ISM of LG dwarfs is examined, revealing differences in HI content, dust, molecular gas, and HII regions. The review also addresses the 'ISM crisis' in dSph galaxies, where some have no detectable gas despite having young stars. The study of LG dwarfs provides insights into galaxy evolution, dark matter, and the role of interactions in shaping galaxy structures. The review concludes that these galaxies remain a key area of study for understanding the evolution of galaxies in the Universe.