Electronic mail, memoranda communicated from one user to others over computer networks. A hypertext structure may be infinitely recursive so that elements in explanations can be investigated in a similar fashion. Hypertext data bases are just becoming widely available, some of them on the internet. A worldwide network of networks permitting email, data base searching, document exchange and other services. Snail mail takes days or longer to travel from place to place.
Email takes seconds, minutes or longer.
A virtual library would consist of all the information materials available to a library patron within and beyond the walls of a literal library thanks to the internet and other computer networks.