Ramadan 2019 is likely to start on Sunday night, with the first day of fast falling on Monday. Several countries have announced the holy month will begin on May 6, including Australia and Turkey.

Saudi Arabia and the UAE are among the Muslim nations whose Moon sighting committees are looking to spot the new Moon. The UAE's committee will convene on Sunday evening.

Ramadan is the ninth month in the Islamic, or Hijri calendar, and the holy month for Muslims, who believe it is when the Quran was revealed to the Prophet Mohammed.

The calendar is determined by Moon phases, which are either 29 or 30 days long, and the appearance of a new Moon signals the beginning of a month. Searching for the new crescent can be a little tricky, however, because it is usually faint and is only visible for about 20 minutes.

Traditionally, the UAE, Bahrain and Saudi Arabia observe the holy month on the same dates, while Oman’s religious authority calls Ramadan independently of the rest of the Arabian Gulf.

Saudi Arabia leads the way in calling the start and end of the holy month, but each country has its own committee to confirm the new Moon.

During this month, Muslims do not consume any food or drinks between fajr (dawn) and maghrib (sunset) prayers – not even water.

Non-Muslims should behave respectfully, remembering to dress conservatively and to not eat, drink or smoke in public during daylight hours.

Working hours will be reduced by two hours per day throughout the month in the private sector and public sector.

Some restaurants will be closed during the holy month and almost all shops will be closed an hour before and a couple of hours after sunset. After iftar, the sunset meal when Muslims break their fast, almost everywhere will be open.

Malls are open during the day and closing times may be as late as midnight or 1am. Some bars and nightclubs may close for the month, while some have licences to stay open.

The Moon sighting committee will reconvene on the 29th day of Ramadan to search for a glimpse of the new crescent Moon. When spotted, the following morning will be announced as the first day of the 10th month, known as Shawwal.