The Wide Area Information Server idea is based on a search model of information, rather than a browse one. Sites that run WAIS servers have created a collection of indexed data that can then be retrieved by searches on these indexes. The access protocol to WAIS servers is based on the standard developed for library searching by ANSI (American National Standards Institute) with the unlikely title, Z39.50 (aka Information Retrieval Service and Protocol Standard).
WAIS has four parts (like most information services except the richer WWW): the client, the server, the database, and the protocol.
Client programs (e.g. the X Windows client xwaisq) construct queries, and send them using the protocol to the appropriate server. The server responds, and includes a 'relevance' measure for the results of the search match to the query.
The actual operation of the protocol is quite complex, as it permits exchanges to be broken in to separate parts. Wais permits retrieval of bibliographic, as well as contents (including images), data.
A search request consists of seed words, or keys if you like, typed by a user into the client, together with a list of documents (identified by a unique global ID). The response is quite complex and includes a list of records, including the following fields: