• Room refers to a private bedroom provided, sometimes with a private ensuite bathroom.
• Board may refer to the food being provided, or alternatively, the table on which food is served.

With a room and board arrangement, the renter has a private bedroom and shares the rest of the house with the person renting out the room. This is different from renting where the renter has private living areas, including a bedroom, bathroom and kitchen.

Two commonly encountered boards are:

• Half Board, where the host provides only breakfast and dinner meals.
• Full Board, where the host provides all three daily meals.

Another option is:

• Bed and breakfast, literally, a place to sleep and where breakfast is provided.

• Bistro, a type of informal French restaurant
• Boarding house, a lodging establishment
• Boarding school
• Parlour boarder, an archaic term for a category of pupil at boarding school
• Sideboard, an article of furniture from which food is served in a dining room

• http://www.phrases.org.uk/bulletin_board/15/messages/521.html
• http://www.funtrivia.com/askft/Question30318.html
• http://www.snopes.com/language/phrases/1500.htm

•   The dictionary definition of room and board at Wiktionary