When does DNA replication occur during cell division?

DNA replication occurs before the actual process of cell division begins, during interphase, which precedes the mitotic phase (M phase). Within interphase, the DNA replication process is carried out during the S phase. This ensures that the chromosomes are fully duplicated before the cell undergoes division. This replication is crucial for both mitosis and meiosis, as it guarantees that each daughter cell will have a complete set of genetic material after division.