Elasticsearch, a core component of the ELK Stack, is built on the Apache Lucene search library, utilizing its syntax to perform complex search queries. Despite Elastic's decision to close source Elasticsearch and Kibana in 2020, AWS responded by creating OpenSearch and OpenSearch Dashboards, which offer features typically available in paid versions of Elasticsearch. The blog discusses different querying methods in Elasticsearch, such as URI search, Request Body Search, and various term-level and compound queries, highlighting their nuances and the flexibility they provide in building complex queries. The document emphasizes the importance of understanding Lucene syntax and Elasticsearch's Query DSL to effectively construct and execute searches, especially given the potential performance impacts of inefficient queries. Additionally, the blog touches on scoring and boosting queries to enhance search relevance and mentions the availability of Logz.io's OpenSearch-as-a-service for improved query performance and management.