> For the complete documentation index, see [llms.txt](https://docs.reya.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.reya.xyz/developers/devnet/reference/market-ids.md).

# Market IDs

Reya identifies markets two ways, and as an integrator you mostly use **symbols**:

* **Symbol** (e.g. `ETHRUSDPERP`, `WETHRUSD`) — what you use almost everywhere: order requests, channel subscriptions (`/v2/market/{symbol}/…`), and the order, execution, depth, and position payloads you receive.
* **`marketId`** — an opaque numeric id you use in just two places: it's **returned by the market-definition endpoints** (the symbol ↔ id mapping), and you **sign it into the EIP-712** [**`OrderDetails`**](/developers/devnet/authentication/signatures-and-nonces.md). Use the value from the market definition as-is — you don't construct or interpret it.