Arbortext Publishing Engine accepts requests and returns responses using the HTTP protocol. The HTTP protocol is a set of rules that allow an exchange of data between an HTTP client program and an HTTP server program. An HTTP client transmits an HTTP request to an HTTP server asking the server to perform some action. After sending the request, the HTTP client waits for the HTTP server to return a response.

HTTP client programs are often referred to as web clients, and HTTP server programs are often referred to as web servers. The most common web client programs are web browsers, such as Microsoft Internet Explorer, Mozilla Firefox, and Opera. While a web browser is probably the most familiar type of web client, any client program that transmits a request using HTTP protocol and receives an HTTP response is a web client.