The document discusses various types of plasmid vectors and cloning vectors used for gene cloning. It describes the key properties required for a vector, including autonomous replication, small size, selectable markers, and restriction enzyme sites. Some examples of early plasmid vectors discussed are pSC101, ColE1, and pBR322. Later vectors with improved properties include the pUC series, pGEM series, and pET series. A variety of vectors were also developed using bacteriophages, cosmids, artificial chromosomes, and more to clone larger fragments.