Graphene, a two-dimensional material with exceptional electronic and mechanical properties, can be significantly affected by structural defects. These defects, which can arise during growth or processing, can either enhance or deteriorate the performance of graphene-based devices. The article reviews the current understanding of point and line defects in graphene, emphasizing the unique ability of graphene to reconstruct its lattice around intrinsic defects, leading to interesting effects and potential applications. Extrinsic defects, such as foreign atoms, are also discussed for their importance in designing graphene-based devices with specific properties. The presence of defects in graphene can alter its electronic, optical, thermal, and mechanical properties. While point defects like vacancies and interstitials have high formation energies, they can still be introduced through irradiation or chemical treatments. Line defects, such as dislocations and grain boundaries, can also affect the material's properties, particularly in polycrystalline graphene. The article discusses various defect types, including the Stone–Wales defect, single and double vacancies, adatoms, and substitutional impurities. These defects can influence the reactivity, electronic structure, and transport properties of graphene. For example, vacancies and adatoms can enhance reactivity, while certain defects can open local bandgaps, affecting the material's electronic properties. The generation of defects in graphene can occur through crystal growth, particle irradiation, and chemical methods. Defects can be created during the growth process, such as through the coalescence of different graphene domains, or by irradiating graphene with energetic particles. Chemical methods, such as oxidation and plasma treatment, can also introduce defects. The electronic properties of defective graphene are significantly affected by the presence of defects. Point defects can create localized states near the Fermi level, while line defects can introduce localized electronic states along their length. These defects can act as scattering centers for electron waves, potentially reducing conductance in graphene ribbons. Overall, the article highlights the importance of understanding and controlling defects in graphene to optimize its performance in various applications, such as electronics and energy conversion devices.Graphene, a two-dimensional material with exceptional electronic and mechanical properties, can be significantly affected by structural defects. These defects, which can arise during growth or processing, can either enhance or deteriorate the performance of graphene-based devices. The article reviews the current understanding of point and line defects in graphene, emphasizing the unique ability of graphene to reconstruct its lattice around intrinsic defects, leading to interesting effects and potential applications. Extrinsic defects, such as foreign atoms, are also discussed for their importance in designing graphene-based devices with specific properties. The presence of defects in graphene can alter its electronic, optical, thermal, and mechanical properties. While point defects like vacancies and interstitials have high formation energies, they can still be introduced through irradiation or chemical treatments. Line defects, such as dislocations and grain boundaries, can also affect the material's properties, particularly in polycrystalline graphene. The article discusses various defect types, including the Stone–Wales defect, single and double vacancies, adatoms, and substitutional impurities. These defects can influence the reactivity, electronic structure, and transport properties of graphene. For example, vacancies and adatoms can enhance reactivity, while certain defects can open local bandgaps, affecting the material's electronic properties. The generation of defects in graphene can occur through crystal growth, particle irradiation, and chemical methods. Defects can be created during the growth process, such as through the coalescence of different graphene domains, or by irradiating graphene with energetic particles. Chemical methods, such as oxidation and plasma treatment, can also introduce defects. The electronic properties of defective graphene are significantly affected by the presence of defects. Point defects can create localized states near the Fermi level, while line defects can introduce localized electronic states along their length. These defects can act as scattering centers for electron waves, potentially reducing conductance in graphene ribbons. Overall, the article highlights the importance of understanding and controlling defects in graphene to optimize its performance in various applications, such as electronics and energy conversion devices.