What is App Script & What is it’s Importance?

Apps Script is a scripting platform developed by Google for light-weight application development in the Google Workspace platform. Google Apps Script was initially developed by Mike Harm as a side project whilst working as a developer on Google Sheets.

Why do we need App Script?
Apps Script is versatile. Among other things, you can: Add custom menus, dialogs, and sidebars to Google Docs, Sheets, and Forms. Apps Script is free to use, and all you need to get started is a Google account. So, if you use Gmail, you can start coding in Apps Script in your browser, for free, right now. If you use Sheets, you can start. If you use Docs, you can start.

Credit : https://www.neenopal.com/GoogleAppScript.html