# Data layer definition

- [Introduction to Sidetree](/data-layer-definition/introduction-to-sidetree.md): A primer on the required capabilities of implementing technologies
- [Entities](/data-layer-definition/entities.md): High-level overview and charts explaining the grand scheme of things
- [Profiles](/data-layer-definition/entities/profiles.md): User identification and relations
- [Research object](/data-layer-definition/entities/research-object.md): The main reference to a publication and its version history
- [Research component](/data-layer-definition/entities/research-component.md): Fractional information about the contents of the data DAG of a research object.
- [Claim](/data-layer-definition/entities/claim.md): A reusable badge to be earned
- [Attestation](/data-layer-definition/entities/attestation.md): The grant or assignment process for a badge
- [Annotation](/data-layer-definition/entities/annotation.md): Social commentary mechanism
- [Relational information](/data-layer-definition/entities/relational-information.md): Additional entities signalling relationships between others
- [Research field](/data-layer-definition/entities/relational-information/research-field.md): Indication that a research object is part of a particular field
- [Contributor](/data-layer-definition/entities/relational-information/contributor.md): Directional link between research object and profile, indicating a contribution.
- [Reference](/data-layer-definition/entities/relational-information/reference.md): Directional link between two publications indicating scientific dependence
- [Metadata](/data-layer-definition/metadata.md): A rich, living repository of arbitrary metadata
- [Deterministic resolution](/data-layer-definition/deterministic-resolution.md): Deterministically resolving an entity instance, including particular versions