> ## Documentation Index
> Fetch the complete documentation index at: https://docs.zbx.boomfi.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# Core Concepts

> Accounts, assets, quotes, orders, and lifecycle for the Trading API.

## Accounts

**Virtual account (parent)**: your organisation's top-level balance account. It aggregates chain-specific sub-accounts (one wallet per chain) that ZBX provisions and manages. Depositing directly to a sub-account's wallet address funds your balance.

**Fiat accounts**: chain-less: your **fiat ledger** holds fiat balances (USD, EUR, GBP). A **fiat external account** is a bank account you register (once per currency) and ZBX verifies: fiat off-ramp settlement is delivered there. See [API guide](/trading/api-guide#fiat-external-accounts) for registration.

Accounts are addressed by numeric `account_id` or by your own `account_reference` string, interchangeably.

## Assets and amounts

An asset is a currency symbol + `chain_id` (for example `USDC` on `137`). Fiat has no chain (`chain_id` omitted or `0`). Token contract addresses are resolved by ZBX on the Quick Trade and Sweep Trade endpoints: you never pass them there (the low-level [RFQ](/trading/advanced-rfq) endpoints use explicit token addresses).

All monetary amounts are **decimal strings** (`"2500.75"`), never floats. Responses round to the asset's precision (commonly 6 dp for many tokens, 2 dp for fiat).

## Quotes and orders

A **quote** (`rfq_…`) is a firm all-in price. Automated quotes are valid for **10 seconds**. Quick Trade requests and accepts the quote in one atomic call, so you never race expiry yourself.

An **order** is the execution of an accepted quote: the unit you track. Terminal success: `status = Closed` with `settlement_status = Completed`.

## Order lifecycle

```mermaid theme={null}
stateDiagram-v2
  [*] --> Open: order accepted
  Open --> Closed: conversion and settlement finish
  Open --> Rejected: terminal failure before completion
  Closed --> [*]
  Rejected --> [*]
```

| status (order) | Meaning                                                                                                               |
| -------------- | --------------------------------------------------------------------------------------------------------------------- |
| `Open`         | Order accepted; conversion and settlement in progress.                                                                |
| `Closed`       | Order fully completed.                                                                                                |
| `Rejected`     | Terminal failure: the order stopped before completion. Funds already credited to your account remain on your balance. |

| settlement\_status  | Meaning                                                       |
| ------------------- | ------------------------------------------------------------- |
| `WaitingDeposit`    | Waiting for an external deposit (72-hour window).             |
| `Processing`        | Funding confirmed; conversion in progress.                    |
| `PendingSettlement` | Converted; proceeds being delivered to the settlement target. |
| `Completed`         | Proceeds delivered: balance credited or paid out on-chain.    |

Trades funded from an existing ZBX balance (normal Quick Trade path) **skip** `WaitingDeposit` and start in `Processing`.

## Next

* [Trading API Guide](/trading/api-guide)
* [Integration Playbook](/trading/integration-playbook)