There are some similarities. But the key difference are: 1) Solid is designed for you to store large, complete sets of data you care about over the protocol. O

There are some similarities. But the key difference are: 1) Solid is designed for you to store large, complete sets of data you care about over the protocol. OpenID is mainly about identity, and the associated bits of metadata are small and can't be written to by the OpenID protocol. 2) Solid separates the data storage from the application provider. So all your data could be in your Solid personal data store, and none in the application provider. (This was normal on Microsoft Windows in the 1990s, so think of it as a cloud version of that model of application development / data storage). This is a high level quick answer - correct me if I've misrepresented something. Quickly looking there are lots of OpenID-related standards that I've never read or used, and I bet some write data!