iCalendar

ICalendar

<p>The <b>Internet Calendaring and Scheduling Core Object Specification</b> (<b>iCalendar</b>) is a <a href="/en/Media_type" title="Media type" class="wl">media type</a> which allows users to store and exchange calendaring and scheduling information such as events, to-dos, journal entries, and free/busy information,<span class="mw-ref reference" id="cite_ref-1"><a href="#cite_note-1" style="counter-reset: mw-Ref 1;"><span class="mw-reflink-text">[1]</span></a></span> and together with its associated standards has been a cornerstone of the standardization and interoperability of <a href="/en/Digital_calendar" title="Digital calendar" class="wl">digital calendars</a> across different vendors. Files formatted according to the specification usually have an <a href="/en/Filename_extension" title="Filename extension" class="wl">extension</a> of <code>.ics</code>. With supporting software, such as an <a href="/en/Email_client" title="Email client" class="wl">email reader</a> or <a href="/en/Calendaring_software" title="Calendaring software" class="mw-redirect wl">calendar application</a>, recipients of an iCalendar data file can respond to the sender easily or counter-propose another meeting date/time. The file format is specified in a <a href="/en/Internet_standard" title="Internet standard" class="mw-redirect wl">proposed Internet standard</a> (<a href="https://tools.ietf.org/html/rfc5545" rel="mw:ExtLink nofollow" class="external mw-magiclink" target="_blank">RFC 5545</a>) for calendar data exchange.<span class="mw-ref reference" id="cite_ref-2"><a href="#cite_note-2" style="counter-reset: mw-Ref 1;" data-mw-group="nb"><span class="mw-reflink-text">[nb 1]</span></a></span></p>

<div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none" about="#mwt1">Computer file format</div>
<style data-mw-deduplicate="TemplateStyles:r1033289096" typeof="mw:Extension/templatestyles mw:Transclusion">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}</style>

<style data-mw-deduplicate="TemplateStyles:r1066479718" typeof="mw:Extension/templatestyles mw:Transclusion">.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent}.mw-parser-output .infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}body.skin-minerva .mw-parser-output .infobox-header,body.skin-minerva .mw-parser-output .infobox-subheader,body.skin-minerva .mw-parser-output .infobox-above,body.skin-minerva .mw-parser-output .infobox-title,body.skin-minerva .mw-parser-output .infobox-image,body.skin-minerva .mw-parser-output .infobox-full-data,body.skin-minerva .mw-parser-output .infobox-below{text-align:center}</style><div class='mobile-collapse'><header class="mobile-collapse-header mobile-collapse-btn"><b>Quick facts: Filename extension, Internet media&nbsp;type,...</b> <span class='arrow'>▼</span></header> <table class="infobox mobile-collapse-element"><caption class="infobox-title" style="padding-bottom:0.15em;">iCalendar</caption><tbody><tr><th scope="row" class="infobox-label" style="line-height:1.2em; padding-right:0.65em;"><a href="/en/Filename_extension" title="Filename extension" class="wl">Filename extension</a></th><td class="infobox-data" style="line-height:1.35em;"><style data-mw-deduplicate="TemplateStyles:r886049734" typeof="mw:Extension/templatestyles">.mw-parser-output .monospaced{font-family:monospace,monospace}</style><div class="monospaced">
.ical, .ics, .ifb, .icalendar</div></td></tr><tr><th scope="row" class="infobox-label" style="line-height:1.2em; padding-right:0.65em;"><a href="/en/Media_type" title="Media type" class="wl">Internet media<span>&nbsp;</span>type</a></th><td class="infobox-data" style="line-height:1.35em;"><div class="monospaced">
text/calendar</div></td></tr><tr><th scope="row" class="infobox-label" style="line-height:1.2em; padding-right:0.65em;">Type of format</th><td class="infobox-data" style="line-height:1.35em;"><a href="/en/Calendar" title="Calendar" class="wl">Calendar</a> data exchange</td></tr><tr><th scope="row" class="infobox-label" style="line-height:1.2em; padding-right:0.65em;"><a href="/en/International_standard" title="International standard" class="wl">Standard</a></th><td class="infobox-data" style="line-height:1.35em;"><style data-mw-deduplicate="TemplateStyles:r1133582631" typeof="mw:Extension/templatestyles">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free a,.mw-parser-output .citation .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited a,.mw-parser-output .id-lock-registration a,.mw-parser-output .citation .cs1-lock-limited a,.mw-parser-output .citation .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription a,.mw-parser-output .citation .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:#d33}.mw-parser-output .cs1-visible-error{color:#d33}.mw-parser-output .cs1-maint{display:none;color:#3a3;margin-left:0.3em}.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}</style>RFC<span>&nbsp;</span><a rel="mw:ExtLink nofollow" href="https://datatracker.ietf.org/doc/html/rfc5545" class="external text" target="_blank">5545</a> <br> (Updated by: RFC<span>&nbsp;</span><a rel="mw:ExtLink nofollow" href="https://datatracker.ietf.org/doc/html/rfc5546" class="external text" target="_blank">5546</a>, RFC<span>&nbsp;</span><a rel="mw:ExtLink nofollow" href="https://datatracker.ietf.org/doc/html/rfc6868" class="external text" target="_blank">6868</a>, RFC<span>&nbsp;</span><a rel="mw:ExtLink nofollow" href="https://datatracker.ietf.org/doc/html/rfc7529" class="external text" target="_blank">7529</a>, RFC<span>&nbsp;</span><a rel="mw:ExtLink nofollow" href="https://datatracker.ietf.org/doc/html/rfc7986" class="external text" target="_blank">7986</a>)</td></tr><tr><th scope="row" class="infobox-label" style="line-height:1.2em; padding-right:0.65em;"><span class="nowrap"><a href="/en/Open_file_format" title="Open file format" class="wl">Open format</a>?</span></th><td class="infobox-data" style="line-height:1.35em;">Yes</td></tr></tbody></table> <footer class='mobile-collapse-footer mobile-collapse-btn'><b>Close</b> <span class='arrow'>▲</span></footer></div>
<figure class="mw-default-size mw-halign-right wiki-thumb"><a href="/en/File:ICalendarSpecification.png" class="mw-file-description image media-thumb" data-hash="File:ICalendarSpecification.png"><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c0/ICalendarSpecification.png/220px-ICalendarSpecification.png" decoding="async" data-file-width="1061" data-file-height="839" data-file-type="bitmap" height="174" width="220" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c0/ICalendarSpecification.png/330px-ICalendarSpecification.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c0/ICalendarSpecification.png/440px-ICalendarSpecification.png 2x" alt="ICalendarSpecification.png"></a><figcaption>iCalendar components and their properties</figcaption></figure>
<p>iCalendar is used and supported by many products, including <a href="/en/Google_Calendar" title="Google Calendar" class="wl">Google Calendar</a>, <a href="/en/Calendar_(Apple)" title="Calendar (Apple)" class="wl">Apple Calendar</a> (formerly iCal), <a href="/en/HCL_Domino" title="HCL Domino" class="wl">HCL Domino</a> (formerly IBM Notes and Lotus Notes),<span class="mw-ref reference" id="cite_ref-3"><a href="#cite_note-3" style="counter-reset: mw-Ref 2;"><span class="mw-reflink-text">[2]</span></a></span> <a href="/en/Yahoo!_Calendar" title="Yahoo! Calendar" class="wl">Yahoo! Calendar</a>, <a href="/en/GNOME_Evolution" title="GNOME Evolution" class="wl">GNOME Evolution</a>, <a href="/en/EM_Client" title="EM Client" class="wl">eM Client</a>, <a href="/en/Lightning_(software)" title="Lightning (software)" class="wl">Lightning</a> extension for <a href="/en/Mozilla_Thunderbird" title="Mozilla Thunderbird" class="wl">Mozilla Thunderbird</a> and <a href="/en/SeaMonkey" title="SeaMonkey" class="wl">SeaMonkey</a>, and partially by <a href="/en/Microsoft_Outlook" title="Microsoft Outlook" class="wl">Microsoft Outlook</a> and <a href="/en/Novell_GroupWise" title="Novell GroupWise" class="mw-redirect wl">Novell GroupWise</a>.</p>

<p>iCalendar is designed to be independent of the transport protocol. For example, certain events can be sent by traditional email or whole calendar files can be shared and edited by using a <a href="/en/WebDav" title="WebDav" class="mw-redirect wl">WebDav</a> server, or <a href="/en/SyncML" title="SyncML" class="wl">SyncML</a>. Simple web servers (using just the HTTP protocol) are often used to distribute iCalendar data about an event and to publish busy times of an individual.  Publishers can embed iCalendar data in web pages using <a href="/en/HCalendar" title="HCalendar" class="wl">hCalendar</a>, a 1:1 <a href="/en/Microformats" title="Microformats" class="mw-redirect wl">microformat</a> representation of iCalendar in semantic <a href="/en/XHTML" title="XHTML" class="wl">(X)</a><a href="/en/HTML" title="HTML" class="wl">HTML</a>.</p>



The Internet Calendaring and Scheduling Core Object Specification 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, iCalendar is used and supported by many products, including Google Calendar, Apple Calendar , HCL Domino , Yahoo! Calendar, GNOME Evolution, eM Client, Lightning extension for Mozilla Thunderbird and SeaMonkey, and partially by Microsoft Outlook and Novell GroupWise. iCalendar is designed to be independent of the transport protocol. 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. Simple web servers are often used to distribute iCalendar data about an event and to publish busy times of an individual.  Publishers can embed iCalendar data in web pages using hCalendar, a 1:1 microformat representation of iCalendar in semantic HTML. 