Google Calendar is a free web based calendar provided by Google. This service is very useful. You can access your appointments on any computer as long as you have an internet connection. Also you can synchronize appointments with your cell phone.
Google Calendar will also synchronize with popular desktop calendars like iCal from Mac OS or Sunbird from Mozilla.
If you already have a Gmail account, you can start using Google Calendar with the same account. And if your friends or co-workers have Google calendar, you can share appointments with them.
You can also synchronize Google Calendar with your cell phone if it's compatible. You can get event reminders and notifications on your cell phone.
If you would like to use Google Calendar, please visit their website.