Rapid transit or mass rapid transit (MRT), also known as metro, is a type of high-capacity public transport that is generally built in urban areas. A rapid transit system that primarily or traditionally runs below the surface may be called a subway, tube, or underground. Unlike buses or trams, rapid transit systems are railways, usually electric, that operate on an exclusive right-of-way, which cannot be accessed by pedestrians or other vehicles. They are often grade-separated in tunnels or on elevated railways.

ಮೆಟ್ರೋ ರೈಲು ಪ್ರಪಂಚದ ಹಲವು ನಗರಗಳಲ್ಲಿ ಆಂತರಿಕ ರೈಲು ಸಾರಿಗೆ ವ್ಯವಸ್ಥೆಯ ಹೆಸರು. "ಮೆಟ್ರೋ" ಪದ ಪ್ಯಾರಿಸ್ನಲ್ಲಿನ Chemin de fer métropolitain de Paris ಎಂಬುದರ ಚಿಕ್ಕ ರೂಪ.