Elasticsearch has been a useful search tool for the speaker's company over the years:
1) They first used it in 2015 for faceted search, moving from Postgres full-text search.
2) In 2016 they built a log monitoring system using the ELK stack.
3) By 2017 they had developed an analytics pipeline for recommendations using Elasticsearch, Logstash, and Kibana.
The speaker discusses how Elasticsearch has scaled well for their needs, provides various search and aggregation capabilities, and discusses best practices for document modeling, indexing performance, and managing index growth over time.