Radiotherapy is treatment using high-energy radiation with the aim to destroy cancer cells. Particles that can be used to deliver such controlled radiation are photons, electrons and protons. Radiotherapy may be used with the intention to cure or in palliative care. Radiotherapy treatment plans need to strike a balance between minimising unwanted effects and maximising wanted effects. For head and neck cancers radiotherapy could be a stand-alone treatment, or could be used in combination with surgery and/or chemotherapy.