Tier 1 visas are working visas granted to exceptional applicants. These visas, once granted, give holders the right to enter the UK and to look for work. A Tier 1 visa is not necessarily tied to work for a single employer. To be granted a Tier 1 visa, the applicant must earn points for her qualifications by holding at least a master's degree. She must also meet previous salary requirements, showing that her earnings in the UK will be high.
The Tier 2 class of visas are sponsored visas. These visas require a specific employer to extend an invitation to the intending immigrant. The employer issues a Certificate of Sponsorship, which is used to apply for the visa. Points are still awarded for qualifications, previous earnings and English language skills. These visas are tied to a specific employer, and it can be difficult to change to a new employer on this type of visa.
Tier 4 visas are for students. To obtain a student visa, the applicant must have a Certificate of Sponsorship from the academic institution. The UKBA inspects and certifies the schools, and only those schools that have legitimate programs are given the right to issue these certificates. Students must meet the points requirement for their category, which is based on the sponsorship of an accredited institution and the student's finances.
Tier 5 visas are for temporary workers, such as students on the BUNAC program, the Youth Mobility Scheme and charity or religious workers. To obtain a Tier 5 visa, the applicant needs a qualified sponsor to issue a Certificate of Sponsorship. Tier 5 visas are issued for a shorter period of time, anywhere from a few weeks to a year.
Visitors do not fall under the points-based system, but they are still required to meet certain criteria before entering the UK. There are reciprocal agreements between the UK and many other countries, which allow travelers to enter without applying for entry clearance beforehand; this is similar to the U.S.'s Visa Waiver Program and allows a stay of up to six months for those who meet the requirements. If a country does not participate in this agreement or a person is ineligible, then the individual needs to apply for entry clearance before traveling to the UK.
