This chapter compares side-by-side the features of the keyword search or information retrieval and the database search. The structured search is conceptualized as a technology for querying multiple data sources in an independent and scalable manner. It occupies the middle ground between keyword search and database search. As in the keyword search paradigm, query originators do not need to know the structure or the number of data sources being queried. As in the database paradigm, users can pose precise queries, control the output order, access data in real time, and manage the data security.