Before 1998, asking for someone's time required asking them.
The digital calendar invitation became a standard feature of office life through a combination of technologies developed in the 1990s. In 1998, the Internet Engineering Task Force published the iCalendar specification (RFC 2445), establishing a universal format for calendar data exchange.1 The specification allowed different software systems to send and receive meeting invitations, creating the interoperability that made the calendar invite ubiquitous.
Before iCalendar, scheduling meetings involved phone calls, emails, or conversations in hallways. An assistant might manage a paper calendar, consulting with counterparts in other offices to find mutually available times. The process was slow, negotiated, and inherently social.
Microsoft Outlook, launched in 1997, was among the first widely adopted applications to integrate calendar invitations into email.2 The software allowed any user to view a colleague's free and busy times and send a meeting request directly. The recipient could accept, decline, or propose a new time with a single click. The negotiation that once required a conversation was reduced to a button.
Google Calendar, launched in 2006, extended the model to the consumer internet, making calendar sharing and invitation standard outside the enterprise.3
The calendar invite shifted control over time. In the paper-calendar era, a meeting required the consent of a gatekeeper, often an assistant, who could protect a schedule from overcommitment. In the digital era, anyone with access to a shared calendar could claim a block of another person's day without a conversation. Meeting density increased accordingly.
By the 2020s, surveys consistently reported that knowledge workers spent an average of 15 or more hours per week in meetings, many of them generated by calendar invitations sent without a stated agenda or a defined outcome. The tool designed to make scheduling efficient had made time itself a commodity that anyone could consume.