According to a
post on one of the company's blogs, the new URL will be
calendar.google.com, with requests to the old
google.com/calendar being automatically redirected to the new one.
This change is scheduled for September 21, and Google expects it to roll out to all customers within three days.
Google engineers did not specify the details of this change, only stating this was "an effort to further increase security."
Considering that GitHub (and many more other services) went through the
same procedures in 2013 for its GitHub Pages services (which changed from
username.github.com to
username.github.io), we presume this was probably done to reinforce the company's protection against CSRF (Cross-Site Request Forgery) and session fixation attacks.
Google did not comment if this change was prompted by a rise in attacks, as a precautionary measure, or just as a cosmetic look, to match the URL scheme of its other products (Photos -> photos.google.com, Hangouts -> hangouts.google.com).
An advisory has also been issued for developers of Chrome extensions and applications that parse content from Google Calendar, urging their creators to update the hard-coded URL from their apps' source code.
Additionally, some users might experience a new wave of notifications, asking them to re-allow access for Google Calendar into their system while the new URL is being rolled out.
