
To develop for MetaMask, install MetaMask in the browser of your choice on your development machine. [Download here](https://metamask.io/).

<Warning title="A quick note">
This guide assumes intermediate knowledge of HTML, CSS, and JavaScript.
</Warning>

Once MetaMask is installed and running (make sure you back up your Secret Recovery Phrase), you should find that new browser tabs have a `window.ethereum` object available in the developer console.
This is how your website will interact with MetaMask.

You can review the full API for that object [here](./ethereum-provider.html).
Note that **over the course of 2020**, we introduced significant changes to this API, and we recommend that you refer to its documentation.

## Basic Considerations

### Web3 Browser Detection

To verify if the browser is running MetaMask, copy and paste the code snippet below in the developer console of your web browser:

<button className="enableEthereumButton btn">Enable Ethereum</button>
<button disabled className="sendEthButton btn">Send Eth</button>

```javascript autorun
if (typeof window.ethereum !== 'undefined') {
  const ethereumButton = document.querySelector('.enableEthereumButton');
  const sendEthButton = document.querySelector('.sendEthButton');

  let accounts = [];

  //Sending Ethereum to an address
  sendEthButton.addEventListener('click', () => {
    ethereum.request({
      method: 'eth_sendTransaction',
      params: [{
        from: accounts[0],
        to: '0x2f318C334780961FB129D2a6c30D0763d9a5C970',
        value: '0x29a2241af62c0000',
        gasPrice: '0x09184e72a000',
        gas: '0x2710',
      }],
    })
      .then((txHash) => console.log(txHash))
      .catch(console.error);
  });

  ethereumButton.addEventListener('click', async () => {
    await getAccount();
    sendEthButton.disabled = false;
    ethereumButton.disabled = true;
  });

  async function getAccount() {
    accounts = await ethereum.request({ method: 'eth_requestAccounts' });
  }
}
```

You can review the full API for the `window.ethereum` object [here](./ethereum-provider.html).
