This framework is a very important part of Elasticsearch. As the name suggests, this framework helps us to do aggregations and generate analytic information on result of a search query. Aggregations help us to get better insight of the data. For example, if we take our library index into account, we can get answers to: How many books in a specific year, which technology, average book per year, and many more.
These aggregations show their power when it comes to gaining insight of system data on a dashboard. Most often system dashboards have aggregated data in form of charts. We will also be using aggregations in later chapters and those aggregations will help Kibana to generate useful visualizations.
There are two types of core aggregations: metrics and buckets. We will learn about these in this section.