Digital libraries offer a knowledge base that can be accessed online, overcoming geographical barriers. They support functions like document preservation, database management, information retrieval, and dissemination. Major digital library projects include those in the US funded by NSF, ARPA, and NASA involving 6 universities, and 35 Elib projects in the UK. In India, the IISc digital library was a pioneer, accessible online and containing publications and theses. However, issues around copyright, data protection, and sustainability must still be addressed before digital libraries fully replace conventional libraries.