Signal flag "Lima" called the "Yellow Jack" which when flown in harbor means the ship is under quarantine. A simple yellow flag (also called the "Yellow Jack") had historically been used to signal quarantine (it stands for Q
among signal flags), but now indicates the opposite, as a signal of a ship free of disease that requests boarding and inspection.
Quarantine is where animals, people or an area of land are isolated to prevent the spread of disease, bacteria or pests.
Images for kids
The quarantine ship Rhin, at large in Sheerness. Source: National Maritime Museum of Greenwich, London
Isolating a village in Romania whose inhabitants believe that doctors poison those suspected of cholera.
Quarantine of the convict ship Surry on the North Shore of Sydney Harbour in 1814, the first quarantine in Australia