In Bangladesh, the main diet consists of rice and dhal (a lentil mixture, which is usually quite thin and poured as gravy over the rice). Depending on the size of income, people will also eat several vegetables and curries. There are for instance many varieties of spinach, also a red one, "lal shak". In Ramadan, the people like to eat sweet and deep fried food. Puffed rice, "muri", is also popular, also throughout the rest of the year.
National dishes are "bhaji" (fried vegetable with turmeric), "jol" (vegetables mixed with fish or meat and a little oil), "kalia" (moderate hot curry with meat and sometimes potato), "korma (kurma))" (a curry which is not hot and contains normally ginger, cardamom and cinnamon), "rezala" (like korma but with almonds, saffron and pistachio), "pullao" (rice and ingredients separately cooked and then fried together), "biryani" (rice, meat, vegetable, yoghurt and spices, first fry and then cook together)  and "kichuri" (rice cooked with lentils, oil and spices).
Bangladesh has many rivers and is bordering the sea, and fish, both from river and sea, and shrimps form an important part of the menu. "Hilsa" is the most popular fish in Bangladesh, it is often served smoked.  Pork is not eaten by the majority of Bangladeshi, as they are Muslim. The Hindu and Christian inhabitants however do eat pork and sometimes you see herds of of small black hairy pigs in the rural areas, which don't look at all like the Dutch pigs I know, the fat, pink, bald, big ones.
The food reminds you of both the Indian and the Nepalese kitchen. Curries are popular, and the food can sometimes be spicy, but not very spicy. Turmeric is popular though, and that is why many dishes are yellowish of color. Cardamom and coriander are also often used.
Sweetmeats are also very popular; they are served as dessert, or with chai (sweetened tea with milk). Hindu people serve them at their Puja festivals. You find many shops with huge collections of (mostly curdled milk based) sweets. Many regions are famous for a certain kind of sweetmeat, and rasmalai for instance is famous in Comilla, whereas rasgolla (rasagolla) for Savar is renowned. When traveling through Bangladesh, someone would always want to bring me to their favorite sweetmeat shop.
Also in other respects you will find regional differences; in the South, people will eat sea fish. Shutki, a form of dried fish, is exported from Chittagong. In Dhaka, people like fried rice and meat, and you can also find more international restaurants, as the living standard is a bit higher than in rural areas. In the old city, biryani is very popular. In the Northern parts, people eat vegetable curries and river fish, but the very poor people sometimes only have plain rice.

Travel in Bangladesh