Many different industries, governments, and the military all rely on the massive computational power that a supercomputer provides and the definition of what makes a computer 'super' is always changing, according to Makeuseof.com.
Because a supercomputer is really just a 'particularly powerful mainframe computer', constant advances in technology mean that the personal computers of today are about as fast as the supercomputers from several decades ago and new systems are forced to push the boundary further continuously.
As of the time of this writing, the fastest supercomputer in the world is China's Sunway TaihuLight which brings an incredible 93.01 petaflops of power by combining over 2.5 million processors into one monumental system. To put this number in perspective, one petaflop is one thousand teraflops, and one teraflop is the speed of the fastest consumer-level processor available on the market today, according to Popular Science. This scale means that the world's fastest computer is 93,010 times faster than the quickest chip money can buy.
These computers are necessary when a lot of data needs to be handled at once to solve a problem. Boeing, as an example, uses them to simulate how aircraft fly through the air to develop better aerodynamics for their designs to increase safety and fuel efficiency. Government agencies, such as The US Department of Defense, were able to use systems like these to create new weather models that more accurately predict hurricanes and cyclones up to five days before they hit land. Meanwhile, the US Army can run simulations of live fire events and prototypes that would be too expensive to build and carry out with real equipment.