In the EU-funded Human Brain Project (HBP), neuroscientists and physicists will attempt the detailed simulation of the entire human brain on a future supercomputer. This requires meeting two enormous challenges: simulating the brain and building the supercomputer to simulate it. Every neuron – perhaps as many as 100 billion – must be represented in the context of its activity in the brain. Each neuron is linked to an average of 10,000 other neurons, which synchronize their activity with each other to varying degrees. “Data” in the brain can travel by different routes depending on the activity. Today’s computers cannot process or store this enormous amount of data and scientists believe that simulating brain circuits in their natural size is necessary to gain solid knowledge. Just think. You’re carrying a supercomputer around with you every day, in your own head.