1. Click stream analysis is used to analyze the electronic paths and page visits of users on websites to understand user behavior and interests. This data comes from e-commerce sites, video sites like YouTube, and other sources. 2. Companies use click stream analysis data for purposes like converting customers, selling products, targeting advertisements, and increasing business growth. Amazon analyzes user behavior data like clicked items and searched videos to target specific ad types to visitors. 3. Hadoop is an open-source framework that handles extremely large and diverse data sets known as "big data." It allows for analysis of click stream and server log data to reveal patterns.