Config Split is an essential module in Drupal 9 for managing multiple configurations across different environments (development, production, staging, etc.). It allows developers to split and isolate specific configurations tailored to each environment, ensuring smoother and more secure management of settings. For instance, configurations like debug mode or cache disabling can be activated only in the development environment, while remaining inactive in production. Config Split also streamlines deployments by enabling the export and import of configurations specific to each environment without overwriting those unique to others. This reduces errors caused by configuration discrepancies between environments and improves development continuity.