IGS
- Graphonomics
- IGS Go server
- Ilkley Grammar School
- Image guided surgery
- Imerslund-Gräsbeck syndrome
- Information Gathering Satellite
- Information Global Service
- Ingolstadt Manching Airport
- Initial Graphics Exchange Specification
- Institute of General Semantics
- Instrument landing system
- InteGraphics Systems
- Interactive geometry software
- Intergenic spacer
- International GNSS Service
- International Glaciological Society
- International Graduates Scheme
- International Grammar School
- Internet Go server
- Ipswich Grammar School
- Irish Georgian Society
- Islington Green School