Eggplant Performance records the requests and responses between the client (usually a browser) and the server to create a recording of the complete conversation. The recording is used by the Web Script Generator to create a web virtual user (VU) script.
During replay of the script, the web VU communicates directly with the server without the need of client software. The web VU script makes calls to the server using Eggplant Performance's web API. As far as the server is concerned, it reacts as if a real client is communicating with it and responds accordingly.
The following video provides an overview of using creating and using web virtual users.