503

503 is an integer that follows 502 and precedes 504. In mathematics, it is a prime number.

In binary, 503 is 111110111. In Roman numerals, it is DIII.

In computing, HTTP status code 503 means Service Unavailable, indicating the server is temporarily unable to handle requests due to overload or maintenance. Sometimes a Retry-After header is included to suggest a wait period before retrying.

In telecommunications, 503 is an area code in the North American Numbering Plan serving northwestern Oregon, including Portland. It is overlaid by the 971 area code.

As a calendar year, 503 CE falls in the early sixth century.

Overall, 503 serves as a reference number with multiple meanings across mathematics, computing, telecommunications, and calendrical notation, depending on the context.