Why Information Retrieval System (IRS) are called as precursor to digital library?
Major differences between Information Retrieval Systems (IRS) and Digital Libraries can largely be attributed to the developments in technology. Most of the IRS were developed for bibliographic databases, therefore, they were restricted to searching metadata or bibliographic information or searching for documents themselves. Moreover, the computer technology that existed at that time did not support full-text searching. The basic unit of an information retrieval system is a document and the focus is on textual retrieval. The IRS worked on exact searching where as digital library are based on pattern searching and inexact searching. While IRS provides metadata access only and digital library provides access to metadata and data. The IRS is, therefore, considered as the precursor to the digital library.
