What does a large yellow X painted on the end of a runway signify?

A large yellow X painted on the end of a runway signifies that the runway is closed. This marking is a safety measure to inform pilots that they should not use that portion of the airfield for takeoffs or landings. The yellow X is universally recognized in aviation to indicate a closed status, which can be due to various reasons such as maintenance, repairs, or other safety concerns. This color and symbol provide a clear and unambiguous indication to pilots from the air and on the ground, ensuring safe operations around the airport.