Which command provides insights into query execution plans?

The command that provides insights into query execution plans is known as "db.collection.explain()". This command is essential for developers and database administrators as it helps them understand how MongoDB executes a query and provides details about the query planning process.

When you use "db.collection.explain()", it returns a document detailing the execution plan for the specified query, including information like which indexes were considered, whether they were used, the number of documents examined, and other performance metrics. This insight is crucial for optimizing queries and improving performance. It allows you to analyze complicated queries and make informed decisions regarding indexing and query structure.

By utilizing "explain", you can also determine if your queries are efficient or if there are any potential issues that could slow down data retrieval. This proactive approach to understanding query behavior ultimately leads to better database performance and user experience.