UK Visitor Visas are required by many foreigners who wish to enter the UK for short stays. Whether you need a visitor visa depends on your nationality, the purpose of your visit and how long you need to stay.
The UK Visitor Visa category includes a number of specific visitor visas that allow people to a holiday, visit family, get married, study a short course, sit the PLAB as well as many other purposes.
Generally, Visitor Visas are valid for 6 months. In some cases, they can be issued for longer periods such as 1, 2, 5 or 10 years. However, those with longer-term visas can still only stay in the UK for periods of six months at a time, other than Academic Visitors and parents of children at school.
You can stay in the UK for up to 6 months with a General Visitor visa. You can also apply for a long-term visit visa if you can prove you need to make repeat visits over a longer period. You can stay for a maximum of 6 months on each visit and your visa can last for 1, 2, 5 or 10 years. This visa entitles holders to visit the UK for up to a maximum of six (6) months allowing them to experience life and culture in the UK. They may be allowed multiple entries to the UK during this six (6) month period.
When you apply you'll need to provide:
a current passport or other valid travel identification evidence that you can support yourself during your trip, eg bank statements or payslips from the last 6 months
You need a page in your passport that's blank on both sides for your visa. Your passport must be valid for the whole of your stay in the UK.