What does "horizontal scaling" refer to in MongoDB?

Horizontal scaling in MongoDB refers to adding additional machines or servers to handle increased load and improve performance. This approach enables the distribution of data across multiple servers, allowing the database to handle a larger volume of requests and store more data. By utilizing multiple hosts, MongoDB can efficiently manage larger workloads and ensure high availability.

This method contrasts with vertical scaling, where additional resources, such as CPU or RAM, are added to an existing server to enhance its performance. Horizontal scaling is particularly beneficial in environments where demand can significantly fluctuate, as it allows for more flexibility in resource management.

In this context, adding machines facilitates a more robust infrastructure, making it possible to accommodate growing datasets and user traffic without being limited by the capacity of a single server.