Explain the three states of a Circuit Breaker in detail.

Closed State:

• Default state where requests flow normally to the downstream service
• Monitors failure rate and response times
• When failure threshold is exceeded, transitions to Open state
  Open State:
• All requests fail immediately without calling the downstream service
• Returns cached data, default values, or error responses
• Has a timeout period before transitioning to Half-Open
• Prevents resource waste and allows downstream service to recover
  Half-Open State:
• Allows a limited number of test requests to check service health
• If test requests succeed, transitions back to Closed
• If test requests fail, returns to Open state
• Acts as a "probe" to determine if the service has recovered