# What is Cyoda?

An Entity Database Management System — a database engine where the first-class abstraction is a stateful entity with schema, lifecycle, history, and transactional integrity.

Cyoda is an **Entity Database Management System (EDBMS)**. Unlike a relational
database, where the unit is a row in a table, and unlike a document database,
where the unit is a JSON blob, Cyoda's first-class unit is an **entity**: a
typed document that carries a lifecycle state, a complete history of every
change, and transactional integrity.

## An EDBMS, not a database

Most databases answer one question well: *what is the state of the world right
now?* They leave you to glue in a workflow engine, a message bus, an audit
layer, and a schema registry on top.

An EDBMS answers a broader question: *how does this thing evolve, under what
rules, and how do I ask what it looked like last Tuesday?* It folds the
workflow engine, the audit trail, the schema registry, and the event contract
into the storage model. Everything the entity does — transitions, rule
evaluations, processor invocations, revisions — is a first-class, queryable
part of the same store.

Out of the box, an entity in Cyoda has:

- a **schema** discovered from ingested samples, evolving over time, lockable;
- a **lifecycle state** governed by a workflow;
- **transactional transitions** that produce durable, addressable revisions;
- a **temporal history** you can query at any point in the past;
- an **audit trail** of every rule, transition, and processor that touched it.

## Why this shape

Cyoda targets domains where state, rules, and data must evolve together:
financial ledgers, order management, regulatory compliance, digital twins.
These domains share a property — "the row got updated" is not enough
information. You need to know *why* it changed, *under what rules*, and what
the world looked like before. That information has to be engineered into a
normal database as an afterthought; an EDBMS makes it the default.

## Two forms today

Cyoda ships in two closely related forms, with the same semantics:

- **cyoda-go** — an open-source Go implementation, run as a local binary or a
  small cluster. Backends are In-Memory, SQLite, or PostgreSQL, chosen at start.
- **Cyoda Cloud** — a managed service backed by the Cassandra-based Cyoda
  Platform Library. Horizontally scalable, multi-tenant, with enterprise
  identity, observability, and provisioning.

Applications written against one run against the other without rewriting the
domain model.

## The growth path

You can start on a laptop in minutes and graduate — on your schedule — to a
container, to Kubernetes, or to Cyoda Cloud as scale and operational needs
demand. The entity, workflow, and API contracts do not change as you move.

<GrowthPathDiagram />

## Where to go next

- [Design principles](/concepts/design-principles/) — the mental model in one
  read.
- [Entities and lifecycle](/concepts/entities-and-lifecycle/) — the state
  machine shape of an entity, including a worked example diagram.
- Digital twins and the growth path — how the same application runs at every
  tier. *(Coming as Concepts fills out.)*