# Entities

**Last Updated:** 2026-02-19
**Confidence:** High

## Summary

Entities are the nodes of the system. Three types: Items (content), Users, and Creators. Every entity has metadata, a vector embedding slot, and an attached signal ledger.

**Key Facts:**
- Items have metadata, embeddings, and signals — signals are typed timestamped streams, not fields
- Users have preferences, histories, and relationships — living profiles that update continuously
- Creators are linked to Items and have their own embeddings (aggregated from catalog)
- Relationships are first-class edges between entities (weighted, directional, traversable)

**File Pointer:** `VISION.md:36-43`

## How It Works

Items enter via the WRITE path with metadata + embedding. A signal ledger is initialized at zero. Cold start exploration budget is applied automatically. Items are immediately queryable after commit.

Users accumulate implicit preference vectors from engagement history. Preference vectors update on every signal write (like, skip, hide, completion).

Creators are entities with their own embeddings derived from their item catalog. Creator-level signals include engagement rate, posting frequency, and follower count.

## Related Topics
- [Signals](./signals.md)
- [Ranking Profiles](./ranking-profiles.md)