The UK Student Visa application process requires an individual to have an offer from a registered UK university, school or educational facility. A person can apply for a Tier 4 Student Visa if they want to study in the UK for a period longer than six months. In this case, the Home Office applies a points-based-system to assess eligibility.
A Tier 4 Visa allows a person to study for a specified course length and allows them to bring a partner or children with them to the UK during their studies.
If the Student Visa application is successful, they generally are permitted to remain in the UK for the full length of your course for a short time after. After this stage, they will need to leave the UK unless they have applied to extend their stay or switch to another immigration category.