The World Health Organization (WHO) classification lists 85 types of primary tumours in the central nervous system, each grouped according to their cell lineage. Simpler classifications exist for various clinical categories. The central nervous system (CNS) comprises both brain and spine, and different tumours are commonly found in one region over another. Children tend to acquire different types of tumours to adults, although some tumours occur in both groups. Primary tumours arise from the local cells in the area, but secondary tumours (metastases) are thought to arrive by haematogenous spread. The grade of the tumour, a histological diagnosis, informs us of its nature in terms of how benign or malignant (invasive/infiltrative) it is, and so helps us predict prognosis. Benign tumours, because of size or position, can be life-threatening. In most cases the mortality rates of CNS tumours have improved over time, but despite the technological advances in medicine there are some groups of tumours whose prognosis has remained unchanged for the past 50 years. We describe the general principles of diagnosing and treating CNS tumours with regard to the common tumour types in each category.