vCalendar is an Internet protocol for interoperability between scheduling programs running on different platforms. vCalendar allows Personal Data Interchange (PDI) programs to exchange scheduling information over the Internet to book meetings, schedule events, and so on. The vCalendar standards define the format by which scheduling information can be exchanged over the Internet.
The basic units of scheduling information are the event, which consists of a scheduled activity and its time, date, and duration, and the to-do, a work item or assignment that is delegated to an individual. vCalendar is defined in Requests for Comments (RFCs) 2445 to 2447 and is broadly supported in the e-mail and groupware industry. The current version is vCalendar 1.0.
Microsoft Outlook 98 and later can import and export information in vCalendar format.