How to not reload webview when resuming app again?

I have made a webview app. Everything works well. However, when user hits back button, and opens (resumes) the app, it reloads the webview. How can I prevent it ?

MainActivity.java

public class MainActivity extends Activity {
    private WebView mWebView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

            mWebView = (WebView) findViewById(R.id.webView);
            mWebView.loadUrl("http://www.example.org");

    }

}