For example, certain events can be sent by traditional email or whole calendar files can be shared and edited by using a WebDav server, or SyncML. ICalendar is designed to be independent of the transport protocol. ICalendar is used and supported by many products, including Google Calendar, Apple Calendar (formerly iCal), HCL Domino (formerly IBM Notes and Lotus Notes), Yahoo! Calendar, GNOME Evolution, eM Client, Lightning extension for Mozilla Thunderbird and SeaMonkey, and partially by Microsoft Outlook and Novell GroupWise.

The file format is specified in a proposed Internet standard (RFC 5545) for calendar data exchange. With supporting software, such as an email reader or calendar application, recipients of an iCalendar data file can respond to the sender easily or counter-propose another meeting date/time. Files formatted according to the specification usually have an extension of.

The Internet Calendaring and Scheduling Core Object Specification ( iCalendar) is a media type which allows users to store and exchange calendaring and scheduling information such as events, to-dos, journal entries, and free/busy information, and together with its associated standards has been a cornerstone of the standardization and interoperability of digital calendars across different vendors. ICalendar components and their properties

Todo calendar