Preservation is recognized as a virtually necessary component of collection development and an area of librarianship that concerns all libraries. Books, millions of books are falling apart. Librarians have increasingly become aware of the impermanence of their collections. Every librarian faces a considerable range of library materials books, prints, maps, micro-forms, photographs, sound recordings, films, videotape, disks that are in various stages of deterioration.
The largest single constituent of library materials is book. There are also various types of non-book reading materials. All these materials both in book form and non-book form are composed of paper. Mainly paper and other constituents of the book create perpetual problem in preserving. 
The maintenance of collections and individual objects should be done as close as possible to original condition through appropriate handling, housing, repair and conservation treatment when appropriate. The librarian who is responsible for the preservation of collection ensures that they are stored under the best possible environmental conditions; determines which materials need special handling or housing to prevent or retard deterioration; and decides which materials are in need of repair or more extensive physical treatment.
It is only recently that librarians have become aware of the gravity of the problems presented by the rapid deterioration of the materials in their care. Specialists from the late 199.1 century on, were aware of the fragility of paper, but it was not until the 1950s that the enormous scope of the problem was recognised — that the bulk of our library materials would disintegrate, if not cared for, by the 21st century.
Library materials are the records of intellectual contribution of the mankind and have been preserved by the human beings for centuries together. The recorded word-etched in stone, inscribed on paper, encoded on magnetic tape — has for centuries served as mankind’s bid for immortality. The survival of thoughts beyond the life of the thinker gives significance to the human experience and so we are comfortable in believing that the materials on which we record those thoughts will live after us.