A dining room is a room for consuming food. Today in Western world dining rooms are adjacent to kitchens to make it easier to serve food. In Medieval times and in many part of world today, we see that dining rooms are on an entirely different floor level.
Surely a dining room can not be without a large dining table and rectangular chairs generally with two arms.
In modern times, we have tables with a removable leaf. It allows larger number of people to have seat. So this part does not take an extra part when not used.
Generally these tables and other furniture of a dining room are made of wood. But there are some people who use more comfortable couches and chairs.
Aside from tables, a dining room would include a set of armchairs and a television. There can be some pictures.
A dining room is not important for many. It is the case especially in houses with an eat-in kitchen. Owners of that kind of houses think that they will use their dining room just 10 days in year. In that case a dining room would have minimal number of furniture.