HTTP Status Code 503 signifies Service Unavailable, which means that the server is temporarily unable to handle the request, usually due to maintenance or overloading. When a server returns HTTP Status Code 503, it indicates that the server is currently unable to process incoming requests but may become available again after some time. This response is often a temporary state, and the client might attempt to retry the request after waiting for a specified period. Server administrators can utilize this status to signal to users and systems that the service is temporarily offline, allowing them to take appropriate actions or wait until the service is restored.