Saved Replies (also called ‘canned responses’) are used to quickly answer common questions. A saved reply is a snippet of text that can be quickly added to the editor when replying to a customer.
Admins are able to edit Saved Replies in mailbox settings by default. To allow regular users edit Saved Replies go to Manage » Settings » General:
Saved Replies can be created on a corresponding page in the mailbox settings.
Categorizing Saved Replies
You can create nested saved replies. In this case parent saved reply will act as some kind of category.