|This article is about an older version of DF.|
A dining room is a room defined from a table. Dwarves prefer to eat in an unassigned dining room (i.e. belonging to "Nobody") sitting in an adjacent chair. They dislike eating on the ground and standing while eating. Dwarves need one tile's worth of table space to put their food on. Thus you cannot put down one table, surround it with four chairs, and expect your dwarves to all eat from that table at the same time. You can put tables next to each other without problems.
Some nobles require a personal dining room, which need only include one table and chair.
If no dining room is available, dwarves will eat at any undefined table. If not even a table is available, they will sit on the ground to eat, which generates an unhappy thought. Eating in a well decorated dining room, however, will generate happy thoughts. Well appointed dining rooms are an easy way to contribute to the happiness of your dwarves.