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

# Core Concepts

> Key ideas to understand the Multi-Layer Security Wallet platform, API, and SDK.

Multi-Layer Security Wallet has a shared set of platform concepts and API/SDK resources. Every action in the web application can be performed via the API and SDK.

## Platform concepts

These concepts describe how assets and governance are organized in the platform:

* **Organizations** are the entities that own accounts and define governance.
* **Members** are people and API members (programmatic identities) in an organization.
* **Groups** are collections of members (for example, a Finance team).
* **Accounts** hold funds and execute on-chain transactions.
* **[Policies](/core-concepts/policies)** describe which transactions are allowed and who can approve them.
* **Admins** are privileged members that can change organization configuration.
* **Transactions** move value or interact with smart contracts from an account.

## API and SDK building blocks

The API and SDK expose the platform concepts as resources and operations:

* **Resources** represent organizations, members, groups, accounts, policies, and transactions.
* **Operations** are proposed changes that require signatures before execution.
* **Signatures** are collected to approve or reject an operation.
* **Execution** applies the proposed change on-chain or within the organization.

## Signing keys

A signing key is the cryptographic key that authorizes an API member to sign operations on behalf
of your organization. You control how your API member signing keys are generated, stored, and
used.

Key generation, storage, and signing should align with your use case, security requirements, and the
policy permissions granted to the API member associated with the signing key.

Common signing setups include:

* Cloud Key Management Services (e.g. AWS KMS, Azure Key Vault, Google Cloud KMS, etc)
* Dedicated Hardware Security Modules (HSMs)
* Cold storage or air-gapped on-premise devices
* Secrets manager environment variables

Contact the Den team for implementation advice tailored to your environment.

## Operation types

The platform exposes two types of operations. Account transactions handle on-chain activity from a specific account, while organization operations handle governance changes. Each type uses different signer roles and approval rules.

| Type                    | Description                                                     | Governed By     |
| ----------------------- | --------------------------------------------------------------- | --------------- |
| Account Transactions    | Value movement and contract interactions for a specific account | Policy rules    |
| Organization Operations | Governance changes like members, groups, policies, and admins   | Admin threshold |

### Account transactions

Account transactions are on-chain actions initiated from an account and governed by a policy. Examples include token transfers, smart contract configuration, and DeFi interactions. The lifecycle is:

1. Propose the transaction with a policy.
2. Collect signatures (approve or reject).
3. Execute once the policy threshold is met.

Key rules:

* A policy must be selected at transaction creation.
* An initiator signature is required to authorize the transaction.
* The initiator signature is distinct from approval or rejection signatures. It must come before other signatures and does not express a decision.

### Organization operations

Organization operations are governance changes such as modifying members, groups, policies, or admins. The lifecycle is:

1. Propose the change.
2. Collect signatures (approve or reject).
3. Execute once the admin threshold is met.

Key rules:

* Only admins can propose, sign, and execute.
* Unlike account transactions, no initiator signature exists.

## Blockchain transaction fees

Blockchain transaction fees are the network costs required to execute transactions on-chain. These fees are sometimes called gas. Den covers these fees. Each plan includes a default fee allowance, and any usage beyond that allowance is billed as overages.