Hereditary diseases are genetic disorders that are passed from one generation to another through inherited genetic material. These disorders may result from mutations in a single gene, abnormalities in chromosomes, defects in mitochondrial DNA, or interactions between multiple genes and environmental factors. Over the last decade, remarkable progress in molecular genetics, genome sequencing, and precision medicine has significantly improved the understanding, diagnosis, and treatment of hereditary diseases. Early diagnosis through genetic testing, prenatal screening, and newborn screening has enabled timely intervention and better disease management. Recent advances in gene therapy and genome-editing technologies, particularly Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas9, have created new opportunities for treating previously incurable inherited disorders. Despite these developments, hereditary diseases continue to impose substantial health, social, and economic burdens worldwide. Ethical issues related to genetic testing, privacy, accessibility, and equitable healthcare also remain major concerns. This review summarizes the molecular basis of hereditary diseases, patterns of inheritance, classification, common hereditary disorders, diagnostic techniques, treatment strategies, recent advances in gene therapy, genetic counselling, and future research directions. The review is written in simple scientific language and aims to provide updated information for students, researchers, healthcare professionals, and clinicians involved in genetics and personalized medicine.