DNA replication and repair are essential processes that maintain genetic stability and ensure accurate transmission of genetic information during cell division. DNA replication is the process by which a cell duplicates its DNA before division. It involves unwinding the double helix, synthesizing new complementary strands by DNA polymerases, and proofreading to minimize errors. Despite high fidelity, replication can introduce mutations, which are corrected by DNA repair mechanisms. These include base excision repair, nucleotide excision repair, mismatch repair, and double-strand break repair through homologous recombination or non-homologous end joining. Efficient DNA repair is crucial for preventing genetic mutations that can lead to diseases such as cancer. Together, DNA replication and repair ensure genome integrity, support cell function, and play vital roles in development, aging, and defense against environmental damage.