Google Add-ons are items that enhance the functioning of the Google Docs, Sheets, and Forms. Add-ons are created by developers to give you features similar to Microsoft Office.
To browse through add-ons for Docs, Sheets and Forms, select Get add-ons in the Add-ons menu of any open Doc, Sheet or Form.
Once you install an add-on it will become available across all of your Docs, Sheets and Forms and you can start using it right away.
Follow my posts this summer as I explore some great Add-ons for Google Docs, Sheets and Forms.