What are the components of ELK Stack?

- E=? Elasticsearch. 
- It is distributed store, search and analytics engine based on Apache lucene. Elasticsearch is where indexing, search and analytics happens. 

- L=? Logstash.
- Collects, aggregates, enrich and ships data to elasticsearch.

- K=? Kibana.
- With Kibana one can explore, visualize the data in elasticsearch.

- There are few more components that can send data to elasticsearch - Beats, APM, external services.

- There are different kind of beats shipper, for eg. filebeat, metricbeat, packetbeat, winlogbeat etc.
- Beats=? For eg. Filebeat can collect data from files in distributed serevrs and send data to the logstash or directly to elasticsearch.

- APM=? Application Performane Monitoring. Capture and analyze distributed transactions in distributed system and sends the captured trace data to elasticsearch.

- External services=? can send data directly to elasticsearch using elasticsearch api end points.