A [[Google Apps Script]] [[web app]] requires either a `doGet` or `doPost` function to return an [HTML service](https://developers.google.com/apps-script/guides/html) `HTMLOUtput` object or a [Content service](https://developers.google.com/apps-script/guides/content) `TextOutput` object. The `doGet` or `doPost` function is run when the app loads. Create the `doGet` function in Code.gs (replace the default function): ```JavaScript function doGet(e){    return HtmlService.createHtmlOutputFromFile('index').evaluate(); } ``` The variable `e` can be used for taking parameters from the url and logging purposes but is not required.