Rl

RL, Rl or rl may refer to:
* Real life phrase (internet slang)
** Real Life, other uses (Disambiguation page for groups films, etc.)

;Complexity classes
* RL, the complexity class of problems solvable by a probabilistic machine in logarithmic space and polynomial time with one-sided error
* NL, another complexity class occasionally referred to as RL

;Locks & Safes
* Registered Locksmith, as awarded by the Associated Locksmiths of America
* Relocker, a mechanism designed to keep a safe locked during a burglary attempt

;People
* R. L. Huggar, a R&B singer
* R. L. Stine, an American author
* Ralph Lauren, American fashion designer

;Technology
* RL circuit, a circuit with a resistor and an inductor
* Reinforcement Learning, a kind of learning in Artificial Intelligence field
* Reduced Level Surveying, the height of a point above the datum

;Other
* Rocket launcher
* Roguelike games, games similar to "Rogue"
* Royal Phnom Penh Airways, IATA airline designator
* Rugby league
* Royal League
* The Acura RL, an automobile
* Reconstituted leaf, a paper-like substance made from small tobacco pieces. See Cigarette
* Réseau Luxembourgeois des Amateurs d'Ondes Courtes, an amateur radio organization in Luxembourg