What documents were stored in ELK?

In ELK (Elasticsearch, Logstash, Kibana), documents typically store structured or semi-structured data, such as:

• Application logs — records of events, errors, requests, and responses.
• System logs — data about the operating system, services, security.
• Monitoring metrics and events — performance indicators, service status.
• Transactional data — if business event analysis is needed.

Each document in Elasticsearch is a JSON object with a set of fields that can be indexed and searched. For example, an HTTP request log might contain fields: timestamp, method, url, status, response_time, etc.

Thus, ELK is used for storing and analyzing large volumes of logs and events, enabling quick search and visualization of data.