The term cloning vectors refer to the DNA molecules that act as transporting vehicle which carries foreign DNA into a host cell for cloning and expression.
An ideal cloning vector should have the desired characteristics like small size (less than 10 kb), polylinker sequence, presence of selectable marker genes, and 'Ori' sequence.
The 'Ori' sequence, stands for origin of replication, is responsible for the initiation of replication process.
In order to link the foreign DNA, the vector needs to have very few, preferably single, recognition sites for the commonly used restriction enzymes. Presence of more than one recognition sites within the vector will generate several fragments, which will complicate the gene cloning process.