Molecular cloning is a laboratory technique used to create copies of specific DNA fragments. This process involves isolating a segment of DNA, often a gene, and inserting it into a vector, such as a plasmid, which can replicate within a host cell. The host, usually a bacterium, then reproduces, creating multiple copies of the inserted DNA. Once the DNA is cloned, researchers can study its function, produce proteins, or even create genetically modified organisms. Molecular cloning is essential in fields like genetics, biotechnology, and medicine, enabling advancements such as gene therapy and the production of recombinant proteins.