DNA replication, the basis for biological inheritance, is a fundamental process occurring in all living organisms to copy their DNA. This process is "semiconservative" in that each strand of the original double-stranded DNA molecule serves as template for the reproduction of the complementary strand. Hence, following DNA replication, two identical DNA molecules have been produced from a single double-stranded DNA molecule. Cellular proofreading and error-checking mechanisms ensure near perfect fidelity for DNA replication. More at Wiki

Definitions: DNA (DeoxyriboNucleic Acid) The nucleic acid that is the genetic material determining the makeup of all living cells and many viruses. It consists of two long strands of nucleotides linked together in a structure resembling a ladder twisted into a spiral. molecule: The smallest particle into which an element or a compound can be divided without changing its chemical and physical properties; a group of atoms that is held together chemically.