Gopher is a service that runs listening for TCP connections on port 70. It responds to trivial string requests from clients with answers preceded by a single character identifying the type, a name, and a selector.
Table 2.9: Gopher Response Types
The client then chooses what to do, and how to display any actual data returned. Gopher+ is a backwards compatible simple extension to gopher to return more complex types of responses, including item size information, the administrator, an abstract, etc. with the item itself. It must be said that gopher and gopher+ are remarkably simple, and yet very powerful ways of building simple information services.