What is a public nuisance?

[Law of Torts] – Public nuisance is an act affecting the public at large, or some considerable portion of it; and it must interfere with rights which members of the community might otherwise enjoy. Acts which seriously interfere with the health, safety, comfort or convenience of the public generally or which tend to degrade public morals have always been considered public nuisance, e.g. carrying on trades which cause offensive smells, or intolerable noises, keeping an inflammable substance like gunpowder in large quantities, etc. They are dealt with by, or in the name of, the State.