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

# Concepts

> Key ideas to understand before integrating Amplify Earn

Before wiring calldata into your product, align on how Amplify Earn models strategies, assets, and execution responsibilities. These concepts shape the SDK helpers referenced throughout the docs.

## Vaults & Yield Types

* **Vault** – On-chain contract that issues ERC-20 shares representing a position in an underlying strategy.
* **Yield Type** – Logical grouping of vaults with similar mandates, exposed as the `YieldType` enum (`CORE`, `TREASURY`, `FRONTIER`).
* **Want Asset** – Token users receive when withdrawing from a vault; often different from the deposit token.

Use `fetchSupportedAssets` to discover active vault configurations, eligible assets, and chain IDs.

## Shares vs. Assets

* Deposits mint **shares** to the recipient. Shares track ownership of the vault.
* Withdrawals burn shares and return the **want asset** using `prepareWithdrawal`.
* Helpers return base-unit values; you provide the human-readable amounts as decimal strings.

## Allowances vs. Permits

* **Unified API (Recommended)**: Use `prepareDepositAuthorization()` to automatically detect the optimal method. It returns the appropriate flow based on token support and existing allowances.
* **Approval flow**: Traditional ERC20 approval using `prepareApproveDepositTokenTxData()` followed by `prepareDepositTxData()`.
* **Permit flow**: When the token supports [EIP-2612](https://eips.ethereum.org/EIPS/eip-2612), sign typed data off-chain and use `prepareDepositWithPermitTxData()` for gas-efficient single-transaction deposits.

The unified API handles method detection automatically—use it for the best developer experience.

## Slippage Controls

* Slippage is expressed in **basis points** (bps). For example, `100` means 1%.
* Deposit helpers default to 50 bps (0.5%).
* WithdrawQueue-based withdrawals do not require slippage or deadline parameters.
* Helpers return minimum acceptable amounts in base units; you can override or disable slippage (not recommended for production).

## Execution Responsibilities

* The SDK **prepares** calldata only; your app decides which signing stack executes it.
* Use viem, wagmi, Privy, or custody flows to send the transaction.
* Handle errors by catching `APIError`, which includes an `endpoint` property (e.g., `prepareDepositWithPermitTxData`).

## Withdrawals

* Use `prepareWithdrawalAuthorization` to determine whether approval is required.
* Use `prepareWithdrawal` to build the withdrawal order transaction.
* For lower-level control, use `prepareWithdrawOrderTxData` and `prepareApproveWithdrawOrderTxData`.

Keep these concepts in mind while following the [Quickstart](./quickstart) or diving into the [API Reference](/v0.4.2/intro/products/earn/developers/api/index).