Apparently my recent Mac 101 column on using Mountain Lion's Calendar has unearthed a lot of questions. Reader Michael Wolfson has one about Calendar and holidays.
I was wondering if there is a way to get the holidays to show up in Calendar (on Mac and/or iPhone). It would be nice to know these things when I look at the calendar.
There is. By default Calendar doesn't come equipped with a holiday calendar, but it's easy to add one through calendar subscriptions. The manual way to do this is to cruise the Internet until you locate the kind of calendar you seek, copy the URL for that calendar, choose File > New Calendar Subscription, and in the sheet that appears enter the copied URL and click Subscribe.
For example, if I wanted to add the San Francisco Giants 2013 baseball schedule to Calendar (and honestly, who wouldn't?) I'd enter this URL: http://mlb.mlb.com/soa/ical/schedule.ics?team_id=137&season=2013. When I click Subscribe I see the calendar name along with its chosen color (you can choose a different one if you like). I can then choose where to add that calendar--on my Mac or to iCloud, for instance. I can additionally choose to remove alerts and attachments and choose how often I want the calendar to refresh--your choices are every five minutes, every fifteen minutes, every hour, every day, and every week. For this specific calendar you'll want it to refresh every day as the calendar is updated to include the previous days' scores.
Because you want this calendar synced to your iPhone as well, you should choose to add it to iCloud. It, along with all your other calendars, will then be synced to your iOS devices.
I've shown you the manual way, but you should have to do this only on rare occasions. And this is because there are lots of websites that offer direct calendar download links. For instance, if you want to add U.S. holidays to Calendar, just travel to Apple's US Holiday Calendar page. When you click on the Download link the calendar will download, Calendar will launch, and you'll be prompted to configure the calendar.
At one time there were sites devoted entirely to providing downloadable calendars but they're no longer being kept up to date. Instead, turn to your favorite search engine and query "download calendar nameofthing" where nameofthing is the schedule or calendar you want to download. What you seek are calendars in the iCalendar format (files in this format end with .ics). This is a calendars standard that can be read by nearly all calendar clients.