Replica Set
A replica set is a group of MongoDB servers that maintain the same data set, providing redundancy and high availability. It consists of one primary node that handles all write operations and multiple secondary nodes that replicate data from the primary, enabling automatic failover if the primary becomes unavailable. This architecture ensures data durability and supports read scalability through secondary nodes.
Developers should use replica sets when building applications that require high availability, fault tolerance, and data redundancy, such as e-commerce platforms, financial systems, or real-time analytics. It is essential for production MongoDB deployments to prevent data loss during hardware failures and to distribute read loads across multiple servers, improving performance and reliability.