A PhD is the most internationally recognised research qualification, and is the most commonly pursued research degree at Leeds. The aim of any research degree is to carry out a programme of research that furthers knowledge in your chosen subject field. During this time, you will work under the supervision of a primary supervisor and one or more co-supervisors who are experts in the same field, sometimes as part of a team, with other students and staff. The Doctor of Philosophy is our main research degree. The PhD is awarded on the basis of a thesis (300 pages or 100,000 words) and examiners must be satisfied that you have discovered, interpreted and communicated new knowledge through original research, worthy of publication in international and national peer reviewed journals, which might reasonably be expected from a competent, hard-working student after three or up to four years of full-time study (five years or up to seven years for part-time or split-site study). Examiners must also be satisfied that you possess good general knowledge in your area of research.