stands for a number of things, including those mentioned below.
- Project Initiation Document defines all major aspects of the project and forms the basis for its management and the assessment of overall success
- Photoionization detector
- Process identifier, a number used by Unix kernels and Windows operating systems to identify a process
- Personal Identifiers, a subset of PII data elements that identify a unique individual and can permit another person to “assume” that individual’s identity without their knowledge or consent.
- Portable Information Device
- PID controller, a control concept used in automation. (Proportional/Integral/Derivative)
- Piping and instrumentation diagram, a technical diagram showing all (or a part of) pipelines, instruments, valves, etc., of a process plant
- Process and instrumentation diagram
- Passive Infrared Detector, a PIR-based motion detector
- Personal Integrating/Indicating Dosemeter, a type of dosimeter for personal use
- Packet Identifier
- Packet ID, used to identify audio/video streams in DVB "Digital Video Broadcasting"
- Pathways Into Darkness, a 1993 video game by Bungie Studios
- Parameter ID, in automotive repair, PIDs are requests for data through an OBD connector
- Paul Is Dead, a rumor in the 1960s that led fans to believe that Paul McCartney was actually dead
- Physician Induced Demand
- Principal ideal domain, in abstract algebra, an integral domain in which every ideal is principal
- "Poverty, Ignorance and Disease", cite in "None Dare Call it a Conspiracy" by Gary Allen.