R

R&

Research and Development

R&

Rest and Relaxation

R&

Research and Testing

R/W

Read/Write[able] (the slash is optional)

RACE

Research and development in Advanced Communication in Europe

RAD

Rapid Application Development

RAID

Redundant Array of Inexpensive Disks

RAM

Random Access Memory

RAP

Rhythm And Poetry

RAS/RAC

Resource Access Client/Resource Access Server (RMS)

RC

RegneCentralen [the Calculation Central, Denmark]

RC

Release Candidate

RDBMS

Relational DBMS

RDF

Resource Description Framework

RDO

Remote Data Objects (Microsoft)

RDS

Radio Data System

REM

Rapid Eye Movements

RFC

Request For Comments

RIAA

Recording Industri Association of America

RIP

Raster Image Processor

RIP

Rest In Peace

RISC

Reduced Instruction Set Computing

RMI

Remote Method Invocation (Java)

RMP

Remote Method Protocol (Java)

RMS

Resource Management System (an OS)

RNA

RiboNucleic Acid

ROFL

Rolling On the Floor Laughing

ROFLMAO

ROFL My Ass Off

ROI

Return On Investment

ROM

Read Only Memory

RPC

Remote Procedure Call

RPE/LTP

Residual Pulse Excitation/Long Term Prediction

RPM

Rotations Per Minute

RPV

Remotely Piloted Vehicle

RSA

Rivest-Shamir-Adelman (data encryption algorithm)

RSC

Referee Stops Contest

RSDL

Reverse-Spiral DL

RTFM

Read The Fucking Manual (The 'F' is optional, but frequently included)

RTL

Radio Tele Luxembourg [Luxemburg Radio and TV]

RTSP

Real Time Streaming Protocol

RV

Recreation Vehicle

RW

See R/W