Answer:
Global cities are locations with the highest concentration of financial power and highly advanced technology infrastructure. It means that many of the worlds economic, financial and technological advancements and inventions are most likely to originate from there.
When new thinking, better products and technologies are invented, their use spread all over the world. Because we are wired to seek better ways or adopt finer solutions to the challenges of life, cities which are at the forefront of solving problems and creating better ways of living exert a major influence on the rest of the world.
Cheers!