In Microsoft Outlook you can automatically add your country’s national holidays.

In the “Tools” menu, select “Options”

In the “Preferences” tab on the Options-screen there is a “Calendar”-section. Click on “Calendar Options”

In the “Calendar options”-section of the Calendar Options (I swear, I’m not making this up) press the “Add Holidays…”-button.

Now a list appears with all the countries for which national holidays are known in Outlook. Select the countries of which you want the holiday information imported in Outlook and click “OK”.