In an Azure blog post, Microsoft announces that they are launching an early preview of a Decentralized IDentity (DID) network called ION (Identity Overlay Network) that is planned to run on Bitcoin. Once completed and running on Bitcoin's main net, ION will allow users to manage and use their digital identities through a decentralized and scalable manner. The blog post notes that there have been many previous incarnations of DID systems that all either suffered from throughput or centralization problems. ION is designed to be open source, decentralized, and highly performant ("tens-of-thousands of DID operations per second").
ION utilizes the Sidetree protocol and IPFS (InterPlanetary File System) for storage. The Sidetree protocol a blockchain-agnostic protocol for creating scalable DID networks and it's developed by Microsoft in collaboration with ConsenSys and Transmute, both members of the Decentralized Identity Foundation (DIF).
Microsoft has open sourced their ION code base by sharing it on GitHub and stated that "[i]n the coming months, [they'll] work with open source contributors and members of identity community to prepare for a public launch of the ION network on Bitcoin mainnet."