Personal Developer Instance (PDI):A free, single-user sandbox instance for learning, exploring, and risky experimentation, not for business use.
Development(DEV):Where developers build new features, customizations, and integrations; isolated from live operations.
Testing:A stable environment to promote code from Dev for functional, integration, and User Acceptance Testing (UAT) by business users, ensuring quality before release.
Production(PROD):The live, real-world environment where end-users access the ServiceNow platform for daily work; no development or testing happens here.
