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, typically a bacterium, then reproduces, creating multiple copies of the inserted DNA. This technique is essential for various applications, including gene expression studies, protein production, and genetic engineering. By using molecular cloning, scientists can better understand the functions of genes and develop new therapies for diseases, making it a vital tool in biotechnology and genetics.