3.2 Search engines

The abundance of digital information has led to the development of an array of new search and discovery technologies. One of the most powerful of these is the ‘search engine’, an information retrieval system allowing users to query a collection of digital data and receive ‘answers’. We’re familiar with the search engines which allow us to retrieve information from the worldwide web, but they are also a ubiquitous part of our interactions with digital data in many other places, including our computers and mobile phones.

Search engines contain two key elements: an index and a query system. The index has much in common with a traditional library catalogue or the index in a book: it provides a list of items and their locations (which folder the file sits in for a database, or their url (web address)). The query system matches human questions to items in the index. You could think of it as an automated librarian or archivist, and the success of the most powerful search engines relies heavily on the query system appearing to know what users want, almost before they articulate it themselves.