Library Collection Development is the process of planning and acquiring a balanced collection of library materials of many formats, including books, periodicals, online resources, and other media.
Collections are developed by librarians and library staff by buying or otherwise acquiring materials over a period of time, based on assessment of the information needs of the library's users. In addition to ongoing materials acquisition, library collection development includes:
the creation of policies to guide material selection
replacement of worn or lost materials
removal (weeding) of materials no longer needed in the collection
planning for new collections or collection areas
cooperative decision-making with other libraries or within library consortia