An aggregator is an entity that collects and analyzes information from different data sources. Aggregation defines a new landscape in information retrieval for goods and services on the Internet.

Examples are presented in this section to illustrate the impact of those well-defined aggregators on their industries. New web-based extraction tools have made it possible for aggregators to easily and transparently gather information from multiple sources with or without the permission or knowledge of the underlying data sources. Mediation technologies allow for automatic comparison of information (e.g., book prices, bank accounts, shipping rates, intelligence information) and agent technologies allow for strategic use of aggregated information.

Examples of aggregators today include information management services that help users manage multiple relationships, consumer education services for making appropriate comparisons of different products, and shopbots for locating the vendor with the lowest price.

Aggregators pose significant threats to existing businesses through the consolidation and comparison of information posted on the World Wide Web. By reducing the consumer's search cost and enabling transparent comparisons across different offerings, aggregators eliminate information asymmetry in the marketplace. In addition, aggregators may also provide important post-aggregation services. By becoming a leading Internet-based intermediary, the emergence of aggregators may completely change the revenue models for many businesses on the Web.