The document discusses the concept of the "Wisdom of the Crowd" and how it applies to analytics contexts where multiple data sources provide different perspectives that together yield more accurate insights than any single source. It then provides an overview of what a business intelligence (BI) stack is, describing it as a logical process for using BI tools and methods to process data through various layers from raw source systems through staging, loading, data warehousing, analytics modeling, and presentation layers. It uses a visual model of a BI stack to illustrate how data moves vertically through these layers, becoming cleaner and simpler at each stage while sacrificing some detail and source system alignment.