Medical education is education related to the practice of being a medical practitioner; either the initial training to become a physician (i.e., medical school and internship), or additional training thereafter (e.g., residency, fellowship and continuing medical education). Medical education is education related to the practice of being a medical practitioner; either the initial training to become a physician (i.e., medical school and internship), or additional training thereafter (e.g., residency, fellowship and continuing medical education). Medical education and training varies considerably across the world. Various teaching methodologies have been utilised in medical education, which is an active area of educational research. Entry-level medical education programs are tertiary-level courses undertaken at a medical school. Depending on jurisdiction and university, these may be either undergraduate-entry (most of Europe, Asia, South America and Oceania), or graduate-entry programs (mainly Australia, North America). Some jurisdictions and universities provide both undergraduate entry programs and graduate entry programs (Australia, South Korea). In general, initial training is taken at medical school. Traditionally initial medical education is divided between preclinical and clinical studies. The former consists of the basic sciences such as anatomy, physiology, biochemistry, pharmacology, pathology. The latter consists of teaching in the various areas of clinical medicine such as internal medicine, pediatrics, obstetrics and gynecology, psychiatry, general practice and surgery. However, medical programs are using systems-based curricula in which learning is integrated, and several institutions do this. In the United States, until quite recently, the requirements for the M.D. degree did not include even one course in human nutrition. Today, this omission has been rectified, at least to the extent that one such course is required. There has been a proliferation of programmes that combine medical training with research (M.D./Ph.D.) or management programmes (M.D./ MBA), although this has been criticised because extended interruption to clinical study has been shown to have a detrimental effect on ultimate clinical knowledge. Following completion of entry-level training, newly graduated doctors are often required to undertake a period of supervised practice before full registration is granted; this is most often of one-year duration and may be referred to as an 'internship' or 'provisional registration' or 'residency'.