This lecture discusses the challenges and opportunities in web search. Some challenges include handling the vast size of the web, ensuring completeness of information coverage, dealing with low-quality information and spams, and managing the dynamic nature of web content. Opportunities include leveraging link analysis and other humanistic factors to improve search results. Techniques such as parallel indexing and searching, spam detection, and robust ranking have been developed to address these challenges. Link analysis techniques are used to enhance search results by leveraging additional information.