iCal and Address Book offer a way to back up their data.
Shared calendars are a handy way to keep groups informed. Here’s how with iCal.
Here’s how to use multiple calendars in iCal, and to find and use calendars other people provide.
As well as keeping track of your appointments iCal can help you organise your To Do list.
How to edit appointments in your iCal calendars.
iCal is a very effective calendar application that comes free with all new Macs.