As computers became increasingly powerful and compact, more and more information became available via computers. The Internet revolutionized this by allowing users to share text files. The library uses the Internet as a gateway to make catalogs and indexes accessible for folks outside of library walls.
Different endings mean different things.
This is what allows you to move within a page or from page to page. When you move over a link a little hand comes up. It has become very cool. Just take a look at The Source webpage.