On the Internet there are three large information services:
- FTP servers give access to a vast amount of software and documentation
through the File Transfer Protocol. They have a (strictly hierarchical)
directory tree structure.
- Gopher servers provide access to information through a menu system.
Menu items may refer to documents or other menus, on the same or another
computer (anywhere on the Internet).
- World Wide Web offers information in hypertext form, mixing (textual)
content and links to documents on the same or other computers (anywhere
on the Internet).
The richer structure of World Wide Web makes it more difficult to reach
all documents than the directory trees for FTP or the menus for Gopher.
