Google Calendar was launched in 2006 as a beta version of an app that quietly showed up on the internet and gained popularity due to its speed, features, and browser-based functionality. The app's natural language processing, multiple calendar management, and Gmail integration were notable early features still used today. Google Calendar has become the most popular calendar service on the web, offering fast and easy-to-use collaboration tools, with integrations available through Zapier with over 1,500 apps. Users can automate tasks such as creating Trello cards from new Google Calendar events or adding Microsoft Outlook appointments to Google Calendar.