| I/B | In-Board |
| I/F | Interface |
| I/O | Input/Output |
| I&AP | Inspect and Analyze Products |
| I&Q | In-Phase & Quadrature |
| I&T | Integration and Test |
| I&TE | Integration and Test Environment |
| I&VT | Imagery and Visualization Team |
| IA | Identification and Authentication (Security) |
| IA | Impact Assessment |
| IA | Independent Assessment |
| IA | Information Assurance |
| IA | Instrument Accommodation |
| IABP | International Arctic Buoy Program |
| IAC | independent assurance contractor |
| IAM | Identity and Access Managment |
| IANA | Internet Assigned Numbers Authority |
| IASI | Infrared Atmospheric Sounding Interferometer |
| IATT | Interim Authority To Test |
| IB | Integrated Baseline |
| IB | InBoard |
| IBIT | Initiated Built In Test |
| IBM | International Business Machines |
| IBPD | Integrated Budget and Performance Document |
| IBR | Integrated Baseline Review |
| IC | Integrated Circuit |
| ICA | Independent Cost Analysis |
| ICA | Integrated Compatibility Analysis |
| ICAO | International Civil Aviation Organization |
| ICB | Instrument Control Box |
| ICD | Interface Control Document |
| ICDL | Instrument Calibration Data List |
| ICE | Independent Cost Estimate |
| ICHC | Inventory and Configuration History Collector |
| ICMP | Internet Control Message Protocol |
| ICP | Integrated C&DH Processor |
| ICPM | Intelligent Copper Pass-Through Module |
| ICS | Industrial Control Systems |
| ICT | Inflight Calibration Target |
| ICT | IR Calibration Target |
| ICT | Integrated Checkout Test |
| ICT | Internal Calibration Target |
| ICWG | Interface Control Working Group |
| IDD | Instrument Definition/Description Document |
| IDD | Interface Design Description |
| IDD | Internet Data Distribution |
| IDE | Integrated Development Environment |
| IDE | Integrated Digital Environment |
| IDL | Interactive Data Language |
| IDP | Intrusion Detection and Prevention |
| IDPS | Intrusion Detection and Prevention Systems |
| IDS | Intrusion Detection System |
| IDT | Integrated Development Team |
| IE | Information Engineering |
| IE | Initiating Event |
| IEC | International Electrotechnical Commission |
| IEEE | Institute of Electrical and Electronic Engineers |
| IEOS | Integrated Earth Observing System |
| IER | Initial Evaluation Review |
| IERS | International Earth Rotation Services |
| IES | Interferometric Editing System |
| IESD | Internal Electrostatic Discharge |
| IETF | Internet Engineering Task Force |
| IF | Interface |
| IF | Intermediate Frequency |
| IFA | Input Filter Assembly |
| IFC | In-Flight Calibration |
| IFDS | Intermediate Frequency Distribution Switching |
| IFDS-SS | Intermediate Frequency Distribution Switch –Switching Software |
| IFFR | Image Frame to Frame Registration |
| IFMS | Integrated Financial Management System |
| IFREMER | Institut Français de REcherche pour l'exploitation de la MER (French Oceanic Institute, Brest) |
| IGBP | International Geosphere-Biosphere Programme |
| IGFOV | Instantaneous Ground Field Of View |
| IGMP | Internet Group Management Protocol |
| IGRF | International Geomagnetic Reference Field |
| IIF | Information in Identifiable Form |
| IIR | Independent Implementation Review |
| IIR | Integrated Independent Review |
| IIRP | Integrated Independent Review Plan |
| IIRT | Integrated Independent Review Team |
| IKE | Internal Key Exchange |
| ILCCA | Independent Life-Cycle Cost Analysis |
| ILED | Intelligent Light Emitting Diode |
| ILO | Integrated Lights Out |
| ILS | Integrated Logistics Support |
| ILSP | |
| ILT | Instructor-Led Training |
| IM | Instrument Manager |
| IMAR | Instrument Mission Assurance Requirements |
| IMC | Image Motion Compensation |
| IMF | Instrument Mounting Frame |
| IMF | Integrated Management Framework |
| IMF | Integrated Master Framework |
| IML | Identity and Access Management |
| IMM | Integrated Management Module |
| IMP | Integrated Management Plan |
| IMPROVE | Interagency Monitoring of Protected Visual Environment |
| IMS | Integrated Master Schedule |
| IMS | Interactive Multisensor Snow and Ice Mapping System |
| INR | Image Navigation and Registration |
| IMU | Inertial Measurement Unit |
| IMWG | Integrated Modeling Working Group |
| InCalD | Instrument Data Calibration |
| INCITS | International Committee for Information Technology Standards |
| INCO | Integration and Checkout |
| IND | Interplanetary Network Directorate |
| INPE | Instituto Nacional de Pesquisas Espaciais |
| INPRG | In Progress |
| INS | Instruction |
| INST CAL | Instrument Calibration Data |
| IO | Information Owner |
| IO | Input/Output |
| IO | Interoperability |
| IOC | Initial Operational Capability |
| IOPS | Input/Output Operations Per Second |
| IORD | NPOESS Integrated Operational Requirements Document |
| IOSEWG | Inter-Organizational Systems Engineering Working Group |
| IOT | In-Orbit Transfer Test/Testing |
| IP | Integrated Process |
| IP | Intellectual Property |
| IP | Internet Protocol |
| IPA | Inter-Program Agreements |
| IPACS | Integrated Polar Acquisition and Control Subsystem |
| IPAMS | IP Address Management System |
| IPAO | Independent Program Assessment Office |
| IPC | Association Connecting Electronics Industries |
| IPC | International Policy Committee |
| IPC | Inter-Process Communications |
| IPD | Individuals and Integrated Product Development Teams |
| IPD | Information Processing Division (OSDPD) |
| IPDU | Internet Protocol Data Unit |
| IPM | Instrument Performance Monitor |
| IPM | Integrated Process Manual |
| IPMI | Integrated Platform Management Interface |
| IPMS | Integrated Program Management Schedule |
| IPO | Integrated Program Office |
| IPP | IP Precedence |
| IPPD | Integrated Product and Process Development |
| IPR | Independent Peer Review |
| IPS | Integrated Product Set |
| IPS | Intrusion Prevention System |
| IPSC | Information Processing Standards for Computers |
| IPT | Integrated Product Team |
| IPU | Integrated Processing Unit |
| IPv6 | Internet Protocol version 6 |
| I/Q | In-phase/Quadrature-phase |
| IQM | Ingest Quality Manager |
| IR | Incident Report |
| IR | Incident Response (Security) |
| IR | infrared |
| IRAB | International Radiosonde/Rawinsonde Observation Mandatory Levels |
| IRAD | Independent Research and Development |
| IRB | Incident Review/Report Board |
| IRD | Interface Requirements Document |
| IRDM | Integrated Requirements and Design Models |
| IRE | Integrated Rate Error |
| IRF | Inertial Reference Frame |
| IRIG | Inter-Range Instrumentation Group |
| IRIS | Incident Reporting Information System |
| IRMA | Integrated Risk Management Application (RM Database) |
| IRMT | Information Resource Management Team |
| IRP | Incident Response Plan |
| IRS | Interface Requirements Specification |
| IRSG | International RAOB Significant Levels |
| IRSST | Infrared Sea Surface Temperature |
| IRT | Independent Review Team |
| IRT | Interim Response Team |
| IRU | Inertial Reference Unit |
| IRVP | Infrared Video Processor |
| IRW | infrared window |
| IS | Information Security |
| IS | Information System |
| IS | Infrastructure |
| IS | Infrastructure System |
| IS | Interface Specification |
| ISA | Interconnected Security Agreement |
| IS-AS | IS Element Application Server |
| ISCCP | International Satellite Cloud Climatology Project |
| ISCS | Infrastructure Consolidated Storage |
| ISD | Instructional System Design |
| ISE | Instrument Systems Engineer |
| ISI | Integral Systems Incorporated |
| ISIQT | Internal Software Item Qualification Test |
| ISL | Inter-Switch Link |
| ISM | Instrument Systems Manager |
| ISM | Internet Service Monitor |
| ISMP | Integrated Schedule Management Plan |
| ISO | International Organization for Standardization |
| ISP | Specific Impulse |
| ISPEC | Instrument Specification |
| ISR | Individual Subcontract Reports |
| ISR | Institute for Scientific Research |
| ISR | Internal Shared Resources |
| ISRS | IS Element Requirement Specification |
| ISS | Internet Security Systems |
| ISSE | Information Systems Security Engineer |
| ISSO | Information System Security Officer |
| ISSP | Information System Security Plan |
| IST | Ice Surface Temperature |
| IST | Integrated System Test |
| IT | Information Technology |
| IT&V | Integration, Test and Verification |
| ITA | Independent Technical Authority |
| ITAM | IT Asset Management |
| ITAR | International Traffic in Arms Regulations |
| ITC | Information Technology Center |
| ITCO | Integration, Test and Checkout |
| ITD | Inception to Date |
| ITE | Integration an Test Environment |
| ITIL | Information Technology Infrastructure Library |
| ITPS | Integrated Trending and Plotting System |
| ITRB | Information Technology Review Board |
| ITS | Information Technology Services |
| ITS | Institute for Telecommunications Sciences |
| ITSM | Information Technology Security Manual |
| ITSO | Information Technology Security Officer |
| ITSP | Information Technology Security Policy |
| ITSPP | Information Technology Security Program Policy |
| ITSWG | IT Security Working Group |
| ITU | International Telecommunication Union |
| ITVWG | Integration, Test, and Validation Working Group - Ground Segment |
| ITWG | Integration and Test Working Group - Flight Project |
| IV&V | Independent Verification and Validation |
| IWG | Instrument Working Group |
| IWP | Ice Water Path |