(NewsNation) — Millions of Muslims worldwide are preparing for the holy month of Ramadan. The month of dawn-to-dusk fasting is intended to bring them closer to God and to remind them of the suffering of those less fortunate.

Here is what you need to know about its significance and how Muslims observe the month.

What is Ramadan?

Ramadan is the ninth month of the Islamic calendar and the most sacred month in Islamic culture, according to National Geographic.

The Muslim holy month is regarded as an act of piety and devotion to God and an exercise in self-restraint.

More than 1.6 billion Muslims, who account for around a quarter of the world’s population, are expected to observe Ramadan.

Muslims believe God began revealing the Quran to the Prophet Muhammad during Ramadan more than 1,400 years ago.

Ramadan culminates in Laylat al-Qadr, or the Night of Destiny, during the last 10 nights of the month, when Muslims engage in intense late-night worship. Muslims believe this was the night God sent the Angel Gabriel to the prophet to reveal the first verses of the Quran.

When is Ramadan?

This year, Ramadan begins on the evening of Sunday, March 10, and ends on the evening of Tuesday, April 9.

Ramadan shifts by about 10 days yearly, Good Housekeeping reports. Next year, the holiday will begin 10 days earlier than this year, on Feb. 28, and will continue to start 10 days earlier each subsequent year.

Islam follows a lunar calendar, so the month begins a week and a half earlier each year, cycling through the seasons, including the long days of hot summers.

The start of the holy month depends on the sighting of the crescent moon by local religious authorities and astronomers and can sometimes vary from country to country.

How long is Ramadan?

Ramadan is the ninth month of the Islamic calendar and lasts 29 or 30 days. Islamic holidays begin and end at sundown, so Ramadan begins at sundown on March 10 and ends at sundown on April 9.

After sunset prayers, family and friends gather for “iftars” — feasts with family and friends that include local holiday treats like candies and nuts.

Mosques and charities set up outdoor banquets where the poor can eat for free each night of Ramadan. Muslims then wake up early for “suhoor,” a small meal eaten just before dawn.

How do Muslims observe Ramadan?

Muslims abstain from all food and drink — not even a sip of water is allowed — and sexual intercourse from dawn to sunset during Ramadan.

Islamic scholars say the merits of fasting also include cultivating gratitude and compassion for the less fortunate and poor.

Making donations and helping feed the needy are hallmarks of the month, which also typically sees the devout dedicating more time to prayers, religious studies and reading of the Quran, the Muslim holy book.

Many look forward to the fast as an act of spiritual rejuvenation and purification.

What are the rules of fasting during Ramadan?

In Islam, fasting is one of The Five Pillars of the faith, along with the profession of faith, prayer, almsgiving, and pilgrimage, known in Arabic as hajj.

There are exceptions made for young children and the sick, as well as women who are pregnant, breastfeeding or menstruating. Travelers are also exempt, including athletes attending tournaments away from home.

Those observing the fast must refrain from eating, drinking, smoking, and sexual intercourse from sunrise to sunset. They are also encouraged to refrain from cursing, fighting, gossip, or road rage throughout the holy month.

Many Muslims, particularly those who live in the U.S. and Europe, are accepting and welcoming of others around them who are not observing Ramadan. They also are not expecting shorter work hours, as is the case in the public sector across much of the Arab world during Ramadan.

Eating or drinking in public during the day is generally frowned upon in Muslim-majority countries. In some, including Saudi Arabia and the United Arab Emirates — home to a large expatriate population in Dubai and Abu Dhabi — it can be punished by fines or imprisonment.

Muslims traditionally break the fast at sunset as the Prophet Muhammad was said to have done, with a sip of water and a few dates.

What is Eid al-Fitr?

After the Ramadan month of fasting, Muslims celebrate the festive three-day holiday Eid al-Fitr, or the Festival of Breaking the Fast, with feasts and family visits. Eid-al-Fitr marks the end of Ramadan and is the second major Islamic holiday. Children are often given new clothes and gifts.

The start of the holiday is traditionally based on sightings of the new moon, which vary according to geographic location.

The Associated Press contributed to this report.