A meta search engine derives its listings by running user queries through multiple other search engines and then summarizing the results. A meta search engine does not maintain its own Index. Listings are displayed by meta search engines either in aggregate or categorized by search engine source.
A metasearch engine (or search aggregator) is an online information retrieval tool that uses the data of a web search engine to produce its own results. Metasearch engines take input from a user and immediately query search engines for results. Sufficient data is gathered, ranked, and presented to the users.
Problems such as spamming reduces the accuracy and precision of results. The process of fusion aims to improve the engineering of a metasearch engine.
Examples of metasearch engines include Skyscanner and Kayak.com, which aggregate search results of online travel agencies and provider websites and Excite, which aggregates results from internet search engines.