The document discusses time intelligence in Power BI. It begins with an introduction to the concept of time intelligence, which allows users to intuitively refer to dates and periods like "last year" or "next month." It then explains that time intelligence functions in Power BI were developed to implement this concept. Finally, it discusses the importance of having a single date table in the data model to serve as the single, absolute measure of time for relating different types of data in BI tools. Proper preparation of the date table is necessary to take advantage of time intelligence functions.