LDP
Also called Linked Data Platform
Linked Data Platform (LDP) is the W3C specification that defines how you read and write Linked Data resources over ordinary HTTP, GET to read a resource, PUT or PATCH to update it, POST to add something to a container, the same verbs the web already uses, applied to structured data instead of web pages. Solid adopted LDP as the mechanism apps use to talk to a Pod: an app doesn't need a Solid-specific SDK to read your calendar or contacts, it can, in principle, do it with the same HTTP methods a browser already knows.
LDP became a W3C Recommendation in 2015, developed by the W3C Linked Data Platform Working Group, separately from, and before, the Solid project existed.
Where Solidus stands
Solidus's own bridge code and API endpoints do not speak LDP, they're a conventional REST API sitting on a JWT+Postgres backend, not LDP containers. Where Community Solid Server is used as a component inside Solidus's Pod product, LDP conformance comes from that component, real software built by the Solid community, not from anything Solidus wrote. We haven't built our own LDP implementation, and we're not claiming to have one.
Proof
Read the Recommendation at w3.org/TR/ldp/. Community Solid Server (github.com/CommunitySolidServer/CommunitySolidServer) is open source and LDP-conformant: its own test suite is the proof, and it's checkable by anyone, independent of Solidus. We don't have a Solidus-authored LDP proof to offer.
Where it comes from
Someone else specified this. Solidus assembles it.
Linked Data Platform became a W3C Recommendation in 2015, developed by the W3C Linked Data Platform Working Group, independently of and before the Solid project existed. Solid adopted it as the read/write mechanism for Pods. Solidus did not write an LDP implementation; where Community Solid Server is used as a component of Solidus's Pod, LDP conformance comes from CSS, not from Solidus's own code.
How to check this
Solidus has not built this. The entry explains the concept.
Read the W3C Recommendation at w3.org/TR/ldp/. Community Solid Server (github.com/CommunitySolidServer/CommunitySolidServer) is open source and LDP-conformant: its own test suite is the proof, checkable by anyone, independent of Solidus. No Solidus-authored LDP proof exists.