About ELK
ELK Stack is a collection of open-source products (Elasticsearch, Logstash, and Kibana) developed, managed, and maintained by Elastic until a few years ago. The ELK application is a combination of Elasticsearch (search and data analysis), Logstash (central logging, log enrichment, and parsing), and Kibana (data visualization). For example, logging user behavior on a shopping site (which browsers customers come from, which countries, which products they visit, etc.) is one of these purposes.
Elasticsearch