China has reached a supercomputing milestone.

The country now has more machines on a list of the world's 500 fastest supercomputers than the U.S.

China has 202 systems on the Top500's supercomputer list, with the U.S. comparatively having only 143.

The U.S. ranking is its lowest since the Top500 rankings began 25 years ago, though the country still manages to come in at second place.

Japan comes in third with 35 supercomputers, and Germany fourth with 20.

According to Top500, China's managed to turn things around pretty fast. Just six months ago, the US led with 169 systems, with China slightly trailing with 160.

How fast is a supercomputer?

Supercomputers have a much higher processing capacity compared to a general-use computer, and a much higher speed of calculation.

They're used for various things such as weather forecasting, nuclear weapons simulation and even to track space activity.

The processing speeds of a supercomputer are measured in floating points operations per second, or "flops".

A "petaflop" is one thousand trillion "flops".

The world's fastest supercomputer, the Chinese Sunway TaihuLight, can reach up to 93 petaflops.

Image: top500/screenshot

That's more than twice as fast as the world's second fastest supercomputer — which is also developed by the Chinese.

The U.S. in comparison, comes in at fifth place with the Titan, at a speed of 17.6 petaflops.

It looks like the U.S. has some serious catching up to do.