Extra-oral appliances are used in orthodontics to apply forces to the jaws, dentition or both and the popularity of these appliances is cyclical. Although the use of retraction headgear for the management of Class II malocclusion has declined over the last 20 years with the refinement of non-compliance approaches, including temporary anchorage devices, headgear still has a useful role in orthodontics. The use of protraction headgear has increased as more evidence of its effectiveness for the treatment of Class lIl malocclusion has become available. This paper describes the mechanics and contemporary uses of headgear in orthodontics for primary care dentists and specialist orthodontists. CPD/CLINICAL RELEVANCE: Extra-oral appliances have specific uses in orthodontic biomechanics. Clinicians using retraction headgear and protraction headgear should be familiar with their clinical indications, the potential problems and how these can be avoided.