Business intelligence (BI) involves collecting data from various sources, analyzing it to gain insights, and presenting the findings to help make better business decisions. It aims to provide the right information to decision-makers at the right time. The document outlines the five stages of BI - collecting data, extracting and transforming it, loading it into a data warehouse, analyzing it, and presenting insights through dashboards, reports and alerts. It also provides examples of how a retail company uses BI tools to gain insights from customer and sales data to improve performance.