iCalendar (.ics)
Also known as: .ics file, iCalendar file, calendar invite file, iCal file
An iCalendar (.ics) file is the standard format for calendar data — events, invitations, and reminders. It is what email invites attach and what apps use to export and subscribe to calendars across platforms.
- Standard file format for calendar events
- Used by email invites and calendar exports
- Works across Apple, Google, and Outlook calendars
What an ICS file holds
A .ics file uses the iCalendar standard to store calendar entries: an event’s title, start and end times, location, attendees, and recurrence rules. Each event sits between BEGIN:VEVENT and END:VEVENT in plain text.
It is how meeting invites travel through email — open the attachment and your calendar offers to add it — and how apps export or publish a calendar others can subscribe to.
Subscriptions and sharing
Beyond one-off files, many calendars are published at an .ics URL you can subscribe to, so updates flow automatically. The same format works across Apple Calendar, Google Calendar, and Outlook.
ICS files are tiny text files. They are a portable, universal way to move events and whole calendars between apps and platforms.