Clinics provide healthcare through appointments or walk-in services, usually without requiring an overnight stay. They may offer general medical care or focus on a particular area, such as dermatology, physiotherapy, sexual health, eye care or mental health. Depending on the clinic, patients can expect consultations, health assessments, advice, diagnosis and treatment for illness or injury, as well as follow-up care and referrals to other health services when needed. Services may include vaccinations, screening, routine health checks, sample collection, diagnostic tests and minor procedures. Some clinics are run by the NHS, while others are privately operated or provide services under contract. The staff and treatments available vary: care may be delivered by doctors, nurses, allied health professionals or other qualified practitioners. Patients may need an appointment, although some clinics accept walk-ins; referral requirements also depend on the service.