A boarding house, also known as a "rooming house" (mainly in the United States) or a "lodging house", is a house (often a family home) in which people on vacation or lodgers rent one or more rooms for one or more nights, and sometimes for extended periods of weeks, months and years. Years ago the boarders would typically share washing, breakfast and dining facilities; in recent years it has become common for each room to have its own washing and toilet facilities. Such boarding houses were often found in English seaside towns (for holidaymakers) and college towns (for students).
In the United Kingdom, the boarding houses were typically run by landladies, and the practice was that boarders would arrange to stay bed-and-breakfast (bed and breakfast only), half-board (bed, breakfast and dinner only) or full-board (bed, breakfast, lunch and dinner). Especially for families on holiday with children, boarding (particularly on a full-board basis) was an inexpensive alternative and certainly much cheaper than staying in any but the cheapest hotels.
Bed and breakfast accommodation (B&B), which exists in many countries in the world (e.g. the UK, the USA, Canada, and Australia), is a specialised form of boarding house in which the guests or boarders normally stay only on a bed-and-breakfast or half-board basis, and where long-stay residence is rare.
Apart from the worldwide spread of the concept of the B&B, there are equivalents of the British boarding houses elsewhere in the world. For example, in Japan, minshuku are an almost exact equivalent although the normal arrangement would be the equivalent of the English half-board. In Hawaii, where the cost of living is high and incomes barely keep pace, it is common to take in lodgers (who are boarders in English terminology) that share the burden of the overall rent or mortgage payable.
You can find a similarity with the Guest House.