State transition testing is a structured testing technique used to validate how a system behaves when moving between different states based on specific inputs or events. Many applications operate through a sequence of states—for example, login systems, order processing workflows, or account status management. State transition testing focuses on verifying that each transition occurs correctly and that the system responds appropriately when moving from one state to another.

This approach is particularly useful for systems where behavior changes depending on previous actions. For instance, an account may move from “active” to “suspended” after multiple failed login attempts, or an order may progress through stages such as “placed,” “processed,” and “shipped.” state transition testing ensures that these transitions follow the expected rules and that invalid transitions are properly restricted.

By modeling system states and the events that trigger transitions, testers can design more structured and comprehensive test cases. This method improves coverage for complex workflows and helps identify logic errors that might not be visible through simple functional testing alone. As a result, state transition testing is widely used in applications where system behavior depends heavily on sequential events and status changes.