Multicultural Indonesia celebrates a vast range of holidays and festivals, but many are limited to small areas (eg. the Hindu festivals of Bali).

The ones to look out for nationwide are Islamic holidays, most notably the fasting month of Ramadhan. During its 30 days, devout Muslims refrain from passing anything through their lips (food, drink, smoke) between sunrise and sunset. People get up early to stuff themselves before sunrise (sahur), go to work late if at all, and take off early to get back home in time to break fast (buka puasa) at sunset.

At the end of the month is the festival of Idul Fitri, also known as Lebaran, when pretty much the entire country takes a week or two off to head back home to visit family; this is the one time of year when Jakarta has no traffic jams, but the rest of the country does, with all forms of transport packed to the gills. All government offices (including embassies) and many businesses close for a week or even two, and traveling around Indonesia is best avoided if at all possible.

Non-Muslims, as well as Muslims travelling (musafir), are exempt from fasting but it is polite to refrain from eating or drinking in public. Many restaurants close during the day and those that stay open maintain a low profile. Bars and other entertainment places either have their opening hours cut, stop selling alcohol or even close entirely. Business travellers will notice that things move at an even more glacial pace than usual and, especially towards the end of the month, many people will take leave.

Christmas (Hari Natal) on December 25, the Western New Year (Tahun Baru) on January 1st and Chinese New Year (Imlek) around February-March are also nationwide public holidays.