# Glossary Source: https://docs.treeship.dev/concepts/glossary > Essential Treeship terms. Every term maps directly to the code. Every term below maps to a concrete type or command in the CLI and Rust core. | Term | Definition | In the code | | ------------------ | ----------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------ | | **Treeship** | A local proof system: one Ed25519 keypair, one artifact store, one identity boundary | Ed25519 keypair + config + local artifact store | | **Actor** | A human or AI that does work, identified by a URI | `human://alice` or `agent://coder` prefix | | **Artifact** | A signed DSSE envelope with a content-addressed `art_` ID. Artifacts chain via `parent_id`. | `Record` in local storage | | **Approval** | Cryptographic authorization for an action, bound by a nonce and constrained by a signed scope (actor / action / subject / max-uses) | `ApprovalStatement` / `treeship attest approval` | | **Hub** | Hosted infrastructure where Treeships share artifacts | treeship.dev API | | **Hub connection** | A named link from your Treeship to a Hub workspace. You can attach, detach, and kill connections independently. | `treeship hub attach` / DPoP keypair | | **Chain** | A linked sequence of artifacts with a common root, connected through `parent_id` references | `treeship verify` walks the chain recursively |