The Human Brain Project (HBP) is a major European scientific research initiative to improve our understanding of the brain and the role it plays in making us human, and to exploit the opportunities offered by the resulting knowledge. The size and complexity of the brain make this an expensive undertaking, but the costs associated with our current ignorance are rising and the potential gains from better insight into the brain are increasing. Brain-related diseases, many of which are age-related, now represent a major part of the global health burden en there are both etical and economic imperatives to keep the growing number of older people healthier and more productive. Economic advantage is increasingly linked to artificial intelligence (AI), our ability to create technology to extract, manipulate and harness knowledge. The HBP's comprehension of what makes the human brain so efficient and flexible should help to maintain Europe's competitiveness and innovation potential in this area. The HBP is one of several brain research initiatives and projects around the world, albeit one of the first, but it is unique in a number of ways. Only the HBP has an explicit focus on both neuroscience and computing. It is also the broadest and most integrated brain initiative, and the only one aiming to build a research infrastructure to accelerate brain research.