For the purposes of this article, I’ll be referring to most powerful  non-distributed computers in the world. Rank is based on a Rmax value (score measured using the LINPACK benchmark suite). Measurements are in petaflops (quadrillions of floating point operations per second). Following list is a current rank as of November/December 2013.

So, what are the five fastest, or most powerful, computers in the world? Who created them, who operates them, and what purposes are they used for?

Tianhe-2 (China - built in 2013)

Rank:** 1; **Rmax: **33.863; **Operating System: Linux (Kylin)

Build was initiated by Chinese government and executed by National University of Defense Technology and Chinese IT firm Inspur. Over 1,300 engineers worked to develop this supercomputer.

Created as an open platform for educational purposes, but also to provide performance computer system for China.

Tianhe-2 is based on Ivy Bridge and 48,000 Xeon Phi boards. It has a total of 3,120,000 cores.

Titan (United States - built in 2012)

Rank:** 2; **Rmax: **17.590; **Operating System: Linux (CLE / SLES)

Built by Cray (Oak Ridge National Laboratory) for use in science projects.  In a way it’s an open platform, as the access depends on the importance of the submitted science project and its potential to exploit Titan’s architecture.

Titan uses 18,688 CPUs, these are paired with an equal number of GPUs.

IBM Sequoia (United States - built in 2013)

Rank:** 3; **Rmax: **17.173; **Operating System: Linux (RHEL)

Built by IBM for Lawrence Livermore National Laboratory (constructed for the National Nuclear Security Administration).

Sequoia is mainly used for simulating nuclear weaponry, but it’s also partially open to scientific community purposes (astronomy, climate research, etc.).

The entire supercomputer is using Linux running on 98,000. It has 98,304 1.6GHz chips housed in its 96 racks, running IBM's 64-bit 18-core processors.

K Computer (Japan - built in 2011)

Rank:** 4; **Rmax: **10.510; **Operating System: Linux

Built by Fujitsu. Primarily used by RIKEN Advanced Institute for Computational Science campus in Kobe, Japan.

It is used for climate and medical research and disaster prevention modeling.

It’s using 88,128 SPARC64 VIIIfx processors - Tofu interconnect.

Mira (United States - built in 2013)

Rank:** 5; **Rmax: **8.586; **Operating System: Linux (RHEL)

Mira supercomputer was funded by the United States Department of Energy  and also by the National Science Foundation. It was constructed by IBM for Argonne National Laboratory's Argonne Leadership Computing Facility.

IBM marketed the supercomputer's speed, claiming that "if every man, woman and child in the United States performed one calculation each second, it would take them almost a year to do as many calculations as Mira will do in one second".