How is DNA replicated, and why is this method of replication important?

DNA is replicated in a semi-conservative manner, which means that both 'parental strands' are used as templates. This ensures that genetic information is passed onto offspring without any changes
(diagram)
DNA helicase breaks apart the hydrogen bonds between interacting base pairs, to form two template strands. After this, free nucleotides are added to the template using the enzyme DNA polymerase, resulting in the formation of two copies of DNA from the parental DNA.