STEP 2: Click the E-Mail Notifications tab. Check the items for which you would like to receive email notifications.

Object Description = Modules available for notifications
To = The Record is "TO" you
CC = You are Copied (CC) on the record
All = Any activity at all, whether you are associated with the record or not.
New = New Record
Mod = Record has been Modified
Note = A new Note has been added
Att = An Attachment has been added.