Camouflage not only provides a backdoor into glimpsing the magnificently diverse sensory worlds of animals, it has also inspired intriguing applications for people.
Over the years the Pugwash conferences evolved into a crucial source of backdoor communications between the superpowers, penetrating the fog of mistrust that characterised the cold war.
Many financial advisers put their clients’ interest first – but some financial advisers get backdoor payments and hidden fees in exchange for steering people into bad investments.