British Naturalisation is the most common way by which a person with foreign citizenship can apply for British citizenship.
If you are naturalised as a British citizen, you will be able to live and work in the UK without being subject to immigration control.
Unless you have a claim to British citizenship based on your ancestry (British citzenship by descent), you will need to apply for British Naturalisation on the basis that you have either spent 5 or 3 years in the UK lawfully, depending on your circumstances.
Eligibility
The eligibility criteria for British Naturalisation depends on your circumstances..
If you are applying for British Naturalisation on the basis of being in the UK for 5 or more years you must:
Multiple Nationalities
UK nationality law allows you to have more than one nationality. However, you should check with the authorities of your original country before you apply for naturalisation, as some countries do not allow you to be a citizen of that country if you are a British citizen.