Google Apps Scripting
Google Apps allows you to create scripts. There are four kinds of scripts:
- Standalone. These are scripts you run directly. You can save these scripts on your Google drive.
- Container based. These are scripts that run within some Google Form, Sheet or Doc. You can also write scripts that are contained within a Google site. The scripts running on this site are Google Apps Scripts contained within this site.
- Spreadsheet custom function. These are scripts that add new functions to Google Sheets.
- HTML Service is a script that works with some HTML file. The HTML file can be static or it can be dynamic. You can actually serve HTML pages using templates similar to PHP where you can imbed your variables within HTML code. You can also use this to modify the user interface of a Google Doc, Sheet or Form.
- UI Service. This allows you to create a page with HTML objects like pushbutton, textboxes, etc and send these to the server for processing.
You can actually interact with Google App services like calendar, drive, email, document, sheet, etc, basically anything within the Google Apps universe.
Once you have created a Web App, you can deploy it and then insert it as a gadget in one of your Google site pages.