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

# Concepts

> Key concepts in the Byzantine infrastructure.

Below are some of the key concepts and terms used in the Byzantine API.

Some of these relate to blockchain technology. Basic knowledge of blockchain will be helpful in understanding Byzantine, but it is not required. Integrating Byzantine is 100% API-based.

## Key terms

| **Concept** | **Explainer**                                                                                                                                                                                                                                                                                                                                  |
| ----------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **User**    | Every individual user and every person in a business entity has a unique `user_id`. User ID is used to identify the user in the Byzantine ecosystem and to update user personal information.                                                                                                                                                   |
| **Entity**  | A legal entity. At least one `root` user account needs to be tied to each legal entity to be able to make transactions. An entity can be found via any `account_id` that is tied to it.                                                                                                                                                        |
| **Account** | Every individual and business user of Byzantine has an account, associated with a unique `account_id`. Accounts can be tied to legal entities.                                                                                                                                                                                                 |
| **Wallet**  | A wallet is the user’s blockchain access point: it stores their assets and enables transactions. The wallet is where a user account's vault shares are held. If a user doesn’t already have one, a secure wallet is automatically created and embedded in their account during onboarding. One account is associated with at least one wallet. |
| **Vault**   | Byzantine products, like Byzantine Prime USDC, are smart contracts known as *vaults*. These smart contracts are blockchain-based code that automatically handles all administration work surrounding a user's deposit. These vaults are what make Byzantine's high security and non-custodial nature possible.                                 |

<Info>
  A `user_id` is tied to a specific email and a specific `integrator_id`. Each email address can only be used once per integrator — attempting to create a second user with the same email will return an error. Refer to [Multi-accounts](/api-reference/multi-accounts) for more details.
</Info>

## Wallet authentication

Even if the user accesses the blockchain through an integrator's interface and Byzantine's API, the user is **sole owner and controller** of their assets. Each time a transaction is to be made, the user must themselves approve it with one of the available signature methods.

Without this signature tied to the user's device or the user's identity, nobody could physically make transactions. In this way, user ownership and control are programmatically guaranteed.

The are two methods of authentication to use the wallet. For more details, see [Authentication methods](/api-reference/authentication-methods).

## Two-step transactions

Since the user is the sole controller of the wallet, they need to sign every transaction themselves. Therefore, making a transaction via the Byzantine API is split into two steps:

1. Requesting the transaction body
2. Submitting the signed transaction

For details on how this process works, see [Transactions](/api-reference/transactions-overview).

## Non-custodiality

At no point in any interaction does Byzantine take custody or hold control over user funds.