What is gene cloning?

The production of a lineage of cells all of which contain one kind of DNA fragment of interest derived from a population of many kinds of DNA fragments. Operationally by:
inserting (recombining) a population of DNA molecules, known to contain the DNA of interest, into a population of vector DNA molecules in such a way that each vector molecule contains only a single DNA molecule from the original population;
transforming a population of host cells with the vector DNA recombinants such that each host cell takes up only one vector;
growing single host cells separately (cloning) by plating at low density to form a collection of separate colonies;
screening the colonies (clones) formed for the presence of the DNA of interest.