Or Image search engine.
Image search is a kind of search engine specialised on finding pictures, images, animations etc. Like the text search, image search is an information retrieval system designed to help find information on the Internet and it allows the user to ask for images etc. using keywords or search phrases and to receive a set of thumbnail images, sorted by relevancy.
Specialized search engines, like in the fields of image search, are among the fastest growing search services on the internet. In 2005 alone the number of image searches increased by 91% (Nielsen/NetRatings 2006-03-31).
Many of the sites that today offer image search uses a service powered by one of the big three; Google, Picsearch or Yahoo.

History
Google at that time on its way on becoming one of the most popular text search engines, naturally had an advantage when, in the summer of 2001, launching their image search as a complement. Their users soon found the new feature and understood to value it.
In addition to their own website, Google offers their image search service to license customers such as other search engines and portals to enable them to complete their own search package. Google image search is today one of the world's largest providers of image search.

Google
The newcomer Picsearch was founded in 2000, and built their business entirely on an image search engine, striving to be the world's first large scale image search engine. Launching their image search in the summer of 2001, at the same time as Google, they soon grew popular among the users on the Internet.
In addition to their own website, Picsearch offers their image search service to license customers such as other search engines and portals to enable them to complete their own search package. Picsearch is today one of the world's largest providers of image search, and is the world's first carbon free search engine.