True about gene library

A DNA library is a set of cloned fragments that collectively represent the genes of a paicular organism. Paicular genes can be isolated from DNA libraries, much as books can be obtained from conventional libraries. The secret is knowing where and how to look. There are two general types of gene library: a genomic library, which consists of the total chromosomal DNA of an organism; and a cDNA library, which represents the mRNA from a cell or tissue at a specific point of time.