for iOS 9.1 software

View the Birthdays calendar. Tap Calendars, then tap Birthdays to
include birthdays from Contacts with your events. If you set up a
Facebook account, you can also include your Facebook friends’
birthdays.
View the Holidays calendar. Tap Calendars, then tap Holidays to
include national holidays with your events.
View events sent to you in Mail messages. Tap Calendars, then tap
Events Found In Mail. To turn off notifications for these events, go to
Settings > Notifications > Calendar > Events Found in Mail.
See multiple calendars at once. Tap Calendars, then select the
calendars you want to view.
Move an event to another calendar. Tap the event, tap Edit, tap
Calendars, then select a calendar to move it to.
Share iCloud calendars
With Family Sharing, a calendar shared with all the members of your
family is created automatically. See . You can also share
an iCloud calendar with other iCloud users. When you share a calendar,
others can see it, and you can let them add or change events. You can
also share a read-only version that anyone can view.
Create an iCloud calendar. Tap Calendars, tap Edit, then tap Add
Family Sharing