Service virtualization creates a simulated version of a service, allowing developers and testers to interact with it as if it were the actual service. This technique helps in scenarios where the service is unavailable due to reasons such as downtime, excessive costs, or complex integration. By using service virtualization, organizations can accelerate the development cycle, reduce dependencies, and improve the quality of applications by testing under realistic conditions. It can be implemented at various levels, such as database, API, and microservices, and is commonly used in Agile and DevOps practices to facilitate continuous integration and deployment.