# Mint

The mint function transfers an asset into the protocol, which begins accumulating interest based on the current [Supply Rate](https://docs.strike.org/stokens/supply-rate) for the asset. The user receives a quantity of sTokens equal to the underlying tokens supplied, divided by the current [Exchange Rate](https://docs.strike.org/stokens/exchange-rate).

**SErc20**

```
function mint(uint mintAmount) returns (uint)
```

* `msg.sender`: The account which shall supply the asset, and own the minted sTokens.
* `mintAmount`: The amount of the asset to be supplied, in units of the underlying asset.
* `RETURN`: 0 on success, otherwise an [Error code](https://docs.strike.org/stokens/error-codes)

Before supplying an asset, users must first [approve](https://eips.ethereum.org/EIPS/eip-20#approve) the sToken to access their token balance.

**SEther**

```
function mint() payable
```

* `msg.value` *\[payable]*: The amount of ether to be supplied, in wei.
* `msg.sender`: The account which shall supply the ether, and own the minted sTokens.
* `RETURN`: No return, reverts on error.

**Solidity**

```
Erc20 underlying = Erc20(0xToken...);     // get a handle for the underlying asset contract
SErc20 sToken = SErc20(0x3FDA...);        // get a handle for the corresponding sToken contract
underlying.approve(address(sToken), 100); // approve the transfer
assert(sToken.mint(100) == 0);            // mint the sTokens and assert there is no error
```

**Web3 1.0**

```javascript
const sToken = SEther.at(0x3FDB...);
await sToken.methods.mint().send({from: myAccount, value: 50});
```