A reminder for an event or a to-do. Alarms may be used to define a reminder for a pending event or an overdue to-do.

A collection of events, to-dos, journal entries, etc. A calendar could be the content of a person or resource’s agenda; it could also be a collection of data serving a more specialized need. Calendars are the basic storage containers for calendaring information.

An entity (often a human) that accesses calendar information.

An application domain that covers systems that allow the interchange, access and management of calendar data.

The Calendaring and Scheduling Consortium consisting of vendors and user groups interested in promoting and improving calendaring and scheduling standards and interoperability.

An atomic realization of Universal Time (UT) or Greenwich Mean Time, the astronomical basis for civil time. Time zones around the world are expressed as positive and negative offsets from UT. UTC differs by an integral number of seconds from International Atomic Time (TAI), as measured by atomic clocks and a fractional number of seconds from UT.

A counter-proposal request a participant may send to an event or task organizer to suggest a change to the event or task such as the scheduled date/time, list of participants, etc.

The period of the year in which the local time of a particular time zone is adjusted forward, most commonly by one hour, to account for the additional hours of daylight during summer months.

A calendar object that usually takes up time on an individual calendar. Events are commonly used to represent meetings, appointments, anniversaries, and day events.

(Bounded) Common free time. This is typically a search generated by an application to show time on a calendar that is available or open.

A database and/or listing of times when a potential attendee or resource is free or busy. Used when scheduling calendar events.

The Internet Calendaring and Scheduling Core Object Specification. An IETF standard (RFC 2445) for a text representation of calendar data.

When used with recurrences, an instance refers to an item in the set of recurring items.

To request the attendance of someone to a calendar event.

Resource conflict resolution. Negotiation is the process of resolving conflicts either programmatically or via direct communication with the participants and invitees of meetings and events.

1. The action of making known, an intimation, a notice.

2. Reminder or alarm sent when any resource or parties interested in the resource need an indicator that some attention is required. Possible notification methods include email, paging, audible signal at the computer, visual indicator at the computer, voice mail, telephone.

The originator of a calendar event typically involving more than one attendee.

Make known publicly calendar information such as freebusy times.

Happening more than once over a specified interval, such as weekly, monthly, daily, etc. See .

An event that happens more than once. You might want an event to occur on a regular basis. To do this you schedule a repeating event. Any changes you make to the event can automatically be made to all occurrences of the event. If necessary, changes can be made to individual events without affecting the others. For example, if you need to attend a weekly meeting, you can schedule a repeating event on your calendar. Using another example, if you want to schedule a five day vacation, schedule an all-day event that repeats daily for a total of five times. If you have to cancel one of the days, delete the one day without deleting the whole event.

See .

Areas of the Earth that have adopted the same local time. Time zones are generally centered on meridians of a longitude, that is a multiple of $15°$, thus making neighboring time zones one hour apart. However, the one hour separation is not universal and the shapes of time zones can be quite irregular because they usually follow the boundaries of states, countries or other administrative areas.