This review by B. T. Draine provides a comprehensive overview of the observed properties of interstellar dust grains, including their wavelength-dependent extinction, optical and infrared emission, scattering, and polarization. The relationship between presolar grains in meteorites and the interstellar grain population is discussed, along with candidate grain materials and abundance constraints. A dust model consisting of amorphous silicate grains, graphite grains, and polycyclic aromatic hydrocarbons (PAHs) is compared with observed emission and scattering data. The review also addresses issues concerning the evolution of interstellar dust. Key topics covered include: - **Extinction**: The wavelength-dependent attenuation of starlight, including absorption features from UV to infrared, and the "pair method" for determining extinction curves. - **Spectroscopy of Dust**: Detailed analysis of spectral features such as the 2175 Å bump, silicate features, diffuse interstellar bands (DIBs), and ice features. - **Polarization**: Optical-UV polarization and polarized far-infrared emission. - **Presolar Grains**: Examination of presolar grains in meteorites and interplanetary dust, including their types and abundances. - **Candidate Grain Materials**: Silicates, carbonaceous materials, SiC, and carbonates are considered as potential grain materials. - **Provisional Grain Model**: A model that includes amorphous silicate grains, graphite grains, and PAHs to explain observed emission and scattering. The review highlights the importance of interstellar dust in shaping the spectra of galaxies and the astrophysics of the interstellar medium, while also discussing the challenges and uncertainties in understanding the composition and evolution of these grains.This review by B. T. Draine provides a comprehensive overview of the observed properties of interstellar dust grains, including their wavelength-dependent extinction, optical and infrared emission, scattering, and polarization. The relationship between presolar grains in meteorites and the interstellar grain population is discussed, along with candidate grain materials and abundance constraints. A dust model consisting of amorphous silicate grains, graphite grains, and polycyclic aromatic hydrocarbons (PAHs) is compared with observed emission and scattering data. The review also addresses issues concerning the evolution of interstellar dust. Key topics covered include: - **Extinction**: The wavelength-dependent attenuation of starlight, including absorption features from UV to infrared, and the "pair method" for determining extinction curves. - **Spectroscopy of Dust**: Detailed analysis of spectral features such as the 2175 Å bump, silicate features, diffuse interstellar bands (DIBs), and ice features. - **Polarization**: Optical-UV polarization and polarized far-infrared emission. - **Presolar Grains**: Examination of presolar grains in meteorites and interplanetary dust, including their types and abundances. - **Candidate Grain Materials**: Silicates, carbonaceous materials, SiC, and carbonates are considered as potential grain materials. - **Provisional Grain Model**: A model that includes amorphous silicate grains, graphite grains, and PAHs to explain observed emission and scattering. The review highlights the importance of interstellar dust in shaping the spectra of galaxies and the astrophysics of the interstellar medium, while also discussing the challenges and uncertainties in understanding the composition and evolution of these grains.