• OB OBligatory Joke
• OBI Online Book Initiative
• OBJ OBligatory Joke
• OC1 Optical Carrier Level 1
• OCIS Organized Crime Information Systems
• OCLC Online Computer Learning Center
• OCR Optical Character Recognition
• OCW Operation Command Word
• OCXs OLE Custom Controls (X stands for Control in this instance)
• ODA Open Document Architecture / Office Document Architecture
• ODAPI Open Database Application Programming Interface
• ODBC Open DataBase Connectivity
• ODI Open Data Link Interface
• ODMA Open Document Management API
• OE Output Enable
• OEM Original Equipment Manufacturer
• OF Overflow Flag
• OH Off Hook
• OIC Oh I See (C)
• OLAP On-Line Analytical Processing
• OLE Object Linking and Embedding
• OLTP OnLine Transaction Processing
• OMG Object Management Group
• OOBE Out Of Box Experience
• OOP Object Oriented Programming
• OOUI Object-Oriented User Interface
• OPC Organic Photoconducting Cartridge
• OPM Other People's Money
• ORAM Optical Random Access Memory
• ORB Object Request Broker
• OS Operating System
• OSDF Open Shortest Data First
• OSF Open Systems Function / Open Software Foundation
• OSI Open Systems Interconnection
• OSPF Open Shortest Path First
• OTF On The Floor
• OTOH On The Other Hand
• OTPROM One-Time Programmable Read-Only Memory
• OTTH On The Third Hand
• OUI Organizationally Unique Identifier
• OUTP OUTput to Port
• OWL Object Window Library