Here is a quick overview on the Standard Visitor Visa:
When to apply: You can apply three months before your travel date. Typically your application will be processed within one month, but allow for as much extra time as possible.
Duration of Stay: You may be able to stay for up to six months on the Standard Visitor Visa.
Cost: Expect to pay about 90 £ (115 USD)
Eligibility: You must always show that you will leave the UL at the end of your trip and that you can support yourself for the duration of your trip (including the return trip, onward journey or any other costs that may arise).
Documents you must provide: A current passport or valid travel identification. Bank statements or payslips from the last six months. Please Note! You need to have certified translations of any documents that aren’t in English or Welsh.
Depending on the exact reason for your travel you may need to show additional documents.
Where to send the documents: When you apply you will be given instructions where you need to submit your papers to.
What else you need to know: You need to know on what date you will be travelling to the UK, where you will be staying, how much the trip will cost you and how much you earn in a year. Also, don’t forget your current home address and how long you have lived there. Your parents’ names and dates of birth are also on that list.
You may need to know additional information depending on the purpose of your travel and whether you have committed any criminal, civil or immigration offences.
How old you need to be: You can travel to the UK if you are under 18 years old, but you will be subject to extra stipulations.
Please keep in mind that this is only an overview and that the particulars of the visa are subject to change. Please check the comprehensive and most up to date information on https://www.gov.uk/browse/visas-immigration. Safe travels!