Learning technology standards support the interoperability, portability, and re-use of learning resources. We present, classify, and explain the main activities in this field, focussing on the standards developed by the Learning Technology Standards Committee of the Institute of Electrical and Electronics Engineers and by the Instructional Management Systems project. We focus on three standards: metadata for learning resources (Learning Object Metadata), learner profiles (Public and Private Information), and interoperability of learning systems (Computer Managed Instruction). We evaluate which standards might be widely used within the next years. Finally, we identify areas for further research and development.