The Comoros has a population of roughly 900,000, spread across three islands (not counting Mayotte, which has its own population of around 320,000 under French administration). The people are a blend of African, Arab, Malagasy, and to a lesser extent Indian and European ancestry, and this mix is visible everywhere -- in faces, food, architecture, and daily customs.
Nearly the entire population is Sunni Muslim, and Islam shapes daily life profoundly. The call to prayer marks the rhythm of the day, Ramadan is strictly observed, and the mosque is the center of community life. Comorian Islam is generally moderate and tolerant, with Sufi influences, though this has been changing somewhat in recent years with the arrival of more conservative interpretations.
The dominant cultural institution, at least on Ngazidja, is the Grand Mariage (anda) -- an elaborate wedding celebration that can last two weeks, involve the entire community, and cost a family tens of thousands of euros. Completing a Grand Mariage is the key to social status: men who have not done so are effectively excluded from village decision-making. Families save for decades, and many Comorians working abroad in France send money home specifically for this purpose. It is an extraordinary tradition to witness if you have the chance.
Comorian (Shikomori) is the language of daily life, with each island speaking its own variant -- Shingazidja, Shimwali, Shindzwani, and Shimaore (on Mayotte). The languages are related to Swahili but distinct from it. French is the language of education and government, and Arabic is used in religious contexts. Comorians are often trilingual.
Hospitality is deeply rooted. Visitors are rare enough to be a genuine novelty, and you will often be invited for tea or food. Dress modestly, particularly in villages and around mosques. Women should cover shoulders and knees. During Ramadan, avoid eating or drinking openly during daylight hours. These courtesies matter and will be appreciated.