Search services are extremely volatile in today's Internet. New search services are being launched continually. Almost as frequently is the rate at which search services upgrade their systems, which often means that their searching interface changes. Finally, while many search services are emerging, there are also a number of services being removed or moved to new sites, leaving and dangling references elsewhere in the Web. MetaCrawler's modular design allows for new services to be added, modified, and removed quickly, thus allowing it to easily adapt to a changing Internet.