Google Calendar, previously code-named "CL2", is a free contact- and time-management web application offered by Google. It allows users to synchronize their Gmail contacts with a web-based calendar. It became available on April 13, 2006 and is currently in beta stages. While users are not required to have a Gmail account, they are required to have a free Google Account in order to use the software.

Features

The interface of Google Calendar is similar to desktop calendar applications such as Microsoft Outlook or iCal on Mac OS X. The Ajax-driven interface enables users to view, add and even drag-and-drop events from one date to another without reloading the page. It sports a variety of view modes, such as the weekly, monthly and agenda views. Users can "quick add" calendar events by typing standard English phrases, such as "Dinner with Michael 7pm tomorrow". Users can also set the number of days to show in their custom view mode. All events in a Google Calendar can be commented on by its users.

Events are stored online, meaning that the calendar can be viewed from many locations. In the case of a user experiencing a hard drive failure, it also means that no data is lost. The application can import Microsoft Outlook calendar files (.csv) and iCalendar files (.ics, the de facto open calendaring file format), although at this stage only when the fields are all in U.S. format.Fact: date=August 2007 Multiple calendars can be added and shared, allowing various levels of permissions for the users. This enables collaboration and sharing of schedules between groups or families. There are also general calendars available for importing into one's account which contain national holidays of various countries.

Google Calendar is integrated with various other Google services:

• Gmail, Google's webmail service. When an e-mail that contains trigger words (such as "meeting", or dates and times) arrives, an "add to calendar" button is automatically displayed alongside it. This feature is not yet available to all Gmail users.
• iGoogle, the user-designed Google homepage, in which users can choose and organize content in the form of "gadgets". The calendar is shown as a module on your homepage. This "gadget" offers options to edit how the time is displayed, which day the week starts on, and a link to "Add Event".Google Calendar Gadget 1
• Google Desktop, Google's desktop search software for Windows Vista, Windows XP and Windows 2000 SP3+ PC or Mac OS X. The mini-calendar gadget allows you view your agenda without having to open your browser. You can place it on your desktop or leave it docked in the sidebar.

Currently, Google Calendar can be synchronized with mobile devices (e.g., BlackBerry, Palm, Pocket PC) or with PC applications (e.g., Microsoft Outlook, Apple iCal) via third party software. Event reminders can be sent via email, as well as SMS to mobile phones in over 80 countries and regions. (Some prepaid services do not support short codes.)