A notification is a record of each time a work request is sent to someone. The notification history serves as a paper trail of the date and time each team member or partner was sent a work request for a Schedule task, To-Do or Warranty item, as well as the status of that work order.
Notifications only go to those people (on your team or partners) who are enabled to receive individual work orders, so simply because an item is assigned to someone does not mean a work request will be sent. You can configure your own profile from the “Personal Settings” link on the main menu. Your partners’ settings are managed from the Partner List, also accessible from the main menu.