DNA replication is a semi-conservative process whereby each strand of the original DNA double helix acts as a template for the production of a new partner strand. This results in two DNA molecules that each contain one original and one newly synthesized strand, preserving half of the original DNA. The key stages of DNA replication are initiation, elongation, and termination, which involve enzymes unwinding and separating the DNA strands before new strands are synthesized according to base-pairing rules between nucleotides.