Many registrars also offer registration through reseller affiliates. An end-user registers either directly with a registrar, or indirectly through one or more layers of resellers. As of 2010, the retail cost generally ranges from a low of about $7.50 per year to about $35 per year for a simple domain registration, although registrars often drop the price far lower – sometimes even free – when ordered with other products.

Sorry Jezelll, had to throw a downvote. This is not what I would consider 'plain english' :( I don't have a problem with the intent of your definition, but using words like 'operation', 'remote server', 'invoked' and 'specification' makes it hard for beginners to understand. See Mitchel Sellers answer as an example of 'plain english'. – Dhaust Jun 30 '09 at 23:53
The gaining Registrar must obtain express authorization from either the Registered Name Holder or the Administrative Contact. A transfer may only proceed if confirmation of the transfer is received by the gaining Registrar from one of these contacts. The authorization must be made via a valid Standardized Form of Authorization, which may be sent e.g. by e-mail to the e-mail addresses listed in the WHOIS. The Registered Name Holder or the Administrative Contact must confirm the transfer. The new registrar starts electronically the transfer of the domain with the help of the authentication code (auth code).
Unlike traditional client/server models, such as a Web server/Web page system, Web services do not provide the user with a GUI. Web services instead share business logic, data and processes through a programmatic interface across a network. The applications interface, not the users. Developers can then add the Web service to a GUI (such as a Web page or an executable program) to offer specific functionality to users.