On our journey of learning about Elastic Stack 7.0, we have gained a strong understanding of Elasticsearch. We learned about the strong foundations of Elasticsearch in the previous two chapters and gained an in-depth understanding of its search use cases.

The underlying technology, Apache Lucene, was originally developed for text search use cases. Due to innovations in Apache Lucene and additional innovations in Elasticsearch, it has also emerged as a very powerful analytics engine. In this chapter, we will look at how Elasticsearch can serve as our analytics engine. We will cover the following topics:

• The basics of aggregations
• Preparing data for analysis
• Metric aggregations
• Bucket aggregations
• Pipeline aggregations

We will learn about all of this by using a real-world dataset. Let's start by looking at the basics of aggregations.