Comprehensive Guide on Salesforce Testing Environment

A Salesforce testing environment is a segregated area of the Salesforce platform that organisations can use to test new functionality, tailor applications, and evaluate integrations in a safe manner without affecting the production live environment. The testing environment is isolated and replicates the production environment and can include replicas of metadata and data for purposes of simulating realistic testing scenarios to ensure quality assurance prior to customer or end-user deployment.

Salesforce offers various types of environments suited for development, testing, and production purposes:
Production Environment: The live environment in which actual users interact with business-critical data and perform daily activities.
Sandbox Environments: Independent copies of the production environment for development, testing, and training without impacting live data. Primary sandbox types include:
Developer Sandbox: Metadata only, best suited for small-scale development and unit testing.
Developer Pro Sandbox: Larger storage than Developer Sandbox, ideal for bigger projects.
Partial Copy Sandbox: Contains metadata and a copy of production data to test particular data situations.
Full Sandbox: Full copy of production org with all data, ideal for performance and user acceptance testing.
Scratch Orgs: Temporary, disposable orgs used primarily by developers for quick testing and development using Salesforce DX tools.