What Is a Bounded Context?

A bounded context is the boundary inside which a particular model is consistent and unambiguous. "Customer" in Sales is not the same shape as "Customer" in Support — and pretending otherwise is where Big Ball of Mud is born.

Inside a bounded context the ubiquitous language is sovereign. Across contexts you translate (anti-corruption layer, published language, etc.).

Two contexts, two definitions of Customer. The dashed line is the anti-corruption layer that translates between them.

Worked example — Mermaid flowchart with subgraph blocks.

To draw bounded contexts in Mermaid you wrap each context's nodes inside a subgraph NAME ... end block, and you connect nodes across subgraphs with arrows:

flowchart LR
  subgraph Sales
    S_Customer[Customer]
    S_Order[Order]
  end
  subgraph Support
    Sp_Customer[Customer]
    Sp_Ticket[Ticket]
  end
  S_Customer -. ACL .-> Sp_Customer

Reading it:

• Two subgraph ... end blocks — one per bounded context.
• Inside, each node has a unique id (S_Customer) and a display label in [...].
• The -. label .-> dashed arrow is the anti-corruption layer translating between the two definitions of Customer.

In the playground below, start from this skeleton and add a third subgraph (e.g. Billing) with at least one node, then connect it to Sales.