BI is the information a business collects about itself. It is normally used to measure and report on the performance of the business in every key area with the aim of helping the business to avoid risks, recognise and grasp opportunities and improve performance.
The “Explained series” is planned to build into a trustworthy collection of explanations and commentaries that can be trusted to tell the story straight without any bias and attempt to make the subjects accessible to the layman. The latter is not always easy as some of these terms refer to genuinely complex subject matter, while others are simply too vague to pin down (there’s another word for that).
If you want an answer on something and you can’t find it easily, please use the comments section to just ask and I will appreciate not having to research the next topic.