Google has updated itself with a new feature for the Gmail users.
Users can now download the mails from their Gmail accounts and can easily save on their local drives. This saved or downloaded mails can also be attached to the mail as a reference, same as you do on your Microsoft Outlook.
As you are already aware of the Undo button, it is to restore the content before the change was made while the Redo button will reverse the changes. These shortcuts are particularly beneficial for those who prefer mouse shortcuts for performing the operations
The Undo and Redo are two of the few functionalities that Gmail users need the most while typing email copies
Google has also introduced another change in its Gmail that is the Redo and undo shortcuts. You will soon be able to see Redo and Undo shortcuts in the Compose window on the task bar.