1. WEB SEARCH BASICS By K.KARTHIKEYAN

2. Web search basics The Web Ad indexes Web spider Indexer Indexes Search User Sec. 19.4.1 2

3. The Web document collection No design/co-ordination Distributed content creation, linking, democratization of publishing Content includes truth, lies, obsolete information, contradictions … Unstructured (text, html, …), semi- structured (XML, annotated photos), structured (Databases)… Scale much larger than previous text collections … but corporate records are catching up Growth – slowed down from initial “volume doubling every few months” but still expanding Content can be dynamically generated The Web Sec. 19.2 3

4. Algorithmic results. Paid Search Ads 4

5. Search on the Web Corpus: The publicly accessible Web: static + dynamic Goal: Retrieve high quality results relevant to the user’s need – (not docs!) Need – Informational – want to learn about something – Navigational – want to go to that page – Transactional – want to do something (web-mediated) Access a service Downloads Shop – Gray areas Find a good hub Exploratory search “see what’s there” Low hemoglobin United Airlines Tampere weather Mars surface images Nikon CoolPix Car rental Finland Abortion morality

6. Search Engines as Info Gatekeepers Search engines are becoming the primary entry point for discovering web pages. Ranking of web pages influences which pages users will view. Exclusion of a site from search engines will cut off the site from its intended audience. The privacy policy of a search engine is important. Introna & Nissenbaum: Defining the Web: The Politics of Search Engines Hindman et al: Googlearchy: How a few Heavily-Linked Sites Dominate Politics on the Web

7. Search Engine Wars The battle for domination of the web search space is heating up! The competition is good news for users! Crucial: advertising is combined with search results! What if one of the search engines will manage to dominate the space?