Tier 4 is part of the points-based system for immigration. It is for migrants who want to study in the UK.
If you are a national of a country outside of the European Economic Area (EEA), you will need a visa or entry clearance to study in the UK.
If the length of your course (or exchange programme) in the UK is shorter than six months, you will need to apply for a Student Visitor Visa. If you are here for longer than six months, you will need to apply for a General Student Visa under Tier 4 of the Points Based System.
In some cases, students can stay in the UK after completing a degree course and take on paid employment.
The Doctorate Extension Scheme is for PhD/Doctorate level students who wish to stay in the UK to work for up to 12 months following the successful completion of their course. Candidates wishing to apply to extend their visa under this scheme are required to use the Tier 4 immigration route.