BEGINVFREEBUSY

BEGIN:VFREEBUSY is an iCalendar component used to convey a calendar user's availability by listing free and busy time periods. It is defined in the iCalendar specification and is commonly employed in scheduling operations, calendar sharing, and availability lookups across calendar systems.

A VFREEBUSY object is typically included inside a VCALENDAR object and describes the time range for which the free/busy information is valid. It can carry identifying properties such as DTSTAMP, DTSTART, and often ORGANIZER or ATTENDEE to indicate who the data refers to and who provided it. The core data are one or more FREEBUSY properties, each representing one or more time intervals. These intervals can be expressed as start/end times (periods) and may be specified in UTC or with local time zones, following the formatting rules of the iCalendar standard.

In practice, VFREEBUSY is used in scheduling workflows to share availability information without exposing event details. It supports responses to meeting requests, availability probes, and free/busy feeds used by client applications and servers (for example in CalDAV or Exchange environments). By aggregating and communicating free and busy slots, it helps participants identify suitable meeting times while minimizing back-and-forth communication.

Privacy and interoperability considerations apply: because VFREEBUSY communicates availability, access control and data minimization are relevant concerns. Not all calendar clients implement every aspect of VFREEBUSY, and representations of time zones and periods may vary between systems. The component is defined by RFC 5545 and is used alongside related mechanisms in iTIP and CalDAV to enable efficient scheduling across platforms. See also iCalendar, RFC 5545, iTIP, and CalDAV.