The basic idea is that it becomes much quicker to view the tasks and events that you have during the day, week or month. Furthermore, creating an event or task is really simple and has a button with which you can access different options.
Furthermore, it supports tabs so as to avoid filling our screen with small windows. Thus making it easier to browse through the information and simplifying the interface.
Sunbird is capable of managing calendars that are shared by several people over the Internet, something that makes it useful to manage meeting and projects that involve team working.
Like the majority of application by Mozilla, Sunbird supports plug-ins and add-ons, small programs that offer new advanced functions to the application. The Firefox browser is a clear example of what can be gained with them.