Muslims around the world are gathering for special events as Eid al-Fitr (usually simply called “Eid”) celebrations are underway.

But what is the holiday all about, how is it being celebrated, and how do you wish someone a happy Eid? Here are five things to know about Eid:

1. What is Eid?

It’s a religious holiday celebrated by Muslims. Traditionally, people gather with relatives and loved ones for special prayers, donate money to charity, and have a feast to mark the end of Ramadan. It’s also a day that people use to reconcile their differences with others, or to forgive someone.

2. Wait, what’s Ramadan?

Ramadan is the Islamic holy month of reflection, when Muslims fast from sunrise to sunset.

3. I’m pretty sure I remember an Eid celebration this past fall. What gives?

You’re right, because there are two Eid celebrations.

Monday marks Eid al-Fitr, the festival of breaking of the fast. The fall celebration was Eid al-Adha, which marks the end of the Hajj pilgrimage to Mecca. That’s expected to fall on a day in October of 2014.

4. So, what day of the year does Eid al-Fitr happen?

That’s a tricky question. Most countries observe Eid when the Shawwal moon, or new moon, can be seen in Saudi Arabia. This year, that is on July 28.

5. How do I wish someone a happy Eid?

Well, “happy Eid” works, but if you want to impress your friend with your newfound knowledge, say “Eid Mubarak,” which roughly translates to “blessed Eid.”