What does sharding in MongoDB refer to?

Sharding in MongoDB refers to the method of distributing data across multiple servers. This approach is essential for managing large datasets and ensuring scalability. By spreading data across different servers, sharding allows MongoDB to handle more data than can fit on a single server and improves overall system performance by enabling parallel processing of queries.

This distributed architecture helps in balancing the load among different servers, so if one server is handling more data or requests than another, the database can scale horizontally by adding more servers to accommodate the workload. This scalability is crucial in modern applications requiring high availability and responsiveness.

In contrast, the other options describe different concepts that do not relate to the distribution of data in this way. Backing up data securely focuses on data protection and recovery, data compression involves reducing the size of data on storage devices without losing information, and indexing refers to improving the speed of data retrieval, which is typically confined to a single server. Understanding sharding is fundamental for working with large-scale applications and ensuring efficient data management in MongoDB.