This article explores atomic defects in monolayer molybdenum disulphide (MoS₂) and their impact on the material's electronic and optical properties. Using a combination of experimental techniques and theoretical calculations, the study identifies and quantifies point defects in MoS₂ samples prepared by mechanical exfoliation (ME), physical vapour deposition (PVD), and chemical vapour deposition (CVD). The results show that the dominant type of defect varies depending on the preparation method: sulphur vacancies are prevalent in ME and CVD samples, while molybdenum antisite defects are dominant in PVD samples. The defect density in PVD samples reaches up to 3.5 × 10¹³ cm⁻², which is significantly higher than in ME and CVD samples. The study also investigates the influence of these defects on the electronic structure and charge-carrier mobility of MoS₂. Ab-initio calculations predict the electronic and magnetic properties of MoS₂ with antisite defects, and the results show that antisite defects can induce a magnetic moment of 2μB. The presence of these defects affects the carrier mobility, with phonon-limited mobility reduced by up to three times in samples with antisite defects. The study highlights the importance of minimizing point defects, particularly antisites, for high-performance electronic applications. The research also discusses the potential of defects in tailoring the properties of MoS₂ for optoelectronic and nanoelectronic applications. The findings suggest that controlling the density and type of defects could lead to novel magnetic and electronic properties in MoS₂. The study provides a comprehensive understanding of the role of point defects in MoS₂ and their impact on the material's performance, which is crucial for the development of high-quality, scalable MoS₂-based electronic devices.This article explores atomic defects in monolayer molybdenum disulphide (MoS₂) and their impact on the material's electronic and optical properties. Using a combination of experimental techniques and theoretical calculations, the study identifies and quantifies point defects in MoS₂ samples prepared by mechanical exfoliation (ME), physical vapour deposition (PVD), and chemical vapour deposition (CVD). The results show that the dominant type of defect varies depending on the preparation method: sulphur vacancies are prevalent in ME and CVD samples, while molybdenum antisite defects are dominant in PVD samples. The defect density in PVD samples reaches up to 3.5 × 10¹³ cm⁻², which is significantly higher than in ME and CVD samples. The study also investigates the influence of these defects on the electronic structure and charge-carrier mobility of MoS₂. Ab-initio calculations predict the electronic and magnetic properties of MoS₂ with antisite defects, and the results show that antisite defects can induce a magnetic moment of 2μB. The presence of these defects affects the carrier mobility, with phonon-limited mobility reduced by up to three times in samples with antisite defects. The study highlights the importance of minimizing point defects, particularly antisites, for high-performance electronic applications. The research also discusses the potential of defects in tailoring the properties of MoS₂ for optoelectronic and nanoelectronic applications. The findings suggest that controlling the density and type of defects could lead to novel magnetic and electronic properties in MoS₂. The study provides a comprehensive understanding of the role of point defects in MoS₂ and their impact on the material's performance, which is crucial for the development of high-quality, scalable MoS₂-based electronic devices.