A casa particular is a Cuban private family establishment that provides tourists paid lodging. A casa particular can be as simple as a room in the house of a Cuban family with basic facilities. But more and more they are private apartments with their own private fully equipped bathrooms and private entrances.
Casa particular literally means "private house" but after the Cuban government in 1997 allowed Cubans to rent out rooms to tourists the term is used for "private accommodations". The decision by Cuban government to allow this type of accommodations was to allow Cubans a legit mean of making an extra income.
Every casa particular is registered with the Cuban government and the family pay taxes to the government over the revenues. They are easily spotted by this sign in their garden or at walls.
The are legal obligated to keep records of whom stays at them and how many nights. All casa particular are regularly checked for hygiene, comfort and integrity of its owners. A casa particular is never owned by a company or business identity but always by a Cuban family. This ensures that when using their service you actively supporting a Cuban family by staying at them.