People who want to enter the UK to live and work must do so by applying to a governmental body known as UK Visas and Immigration. The regulations that control who can enter the country and for how long are part of immigration law.
Qualifying to Enter the UK
Everyone who enters the UK from another country must meet certain requirements. Those requirements change depending on where people are from, how long they want to stay in the UK, and what they want to do there. For instance, the requirements for someone entering the country for a month-long holiday are different from the requirements for someone who wants to live and work in the UK permanently.
Everyone who enters the country must have a visa, which is obtained via UK Visas and Immigration. There are different ways to qualify for a visa depending on things like marital status and country of origin.
If you're married to or in a civil partnership with a UK resident you can get a spousal visa.
Family visas apply if you have a parent or child living in the UK, or another family member who is willing to be responsible for your welfare.
If you're from a European Economic Area country you can stay in the UK provided you're financially independent, have work, or are studying.
For non-EEC residents, immigration is subject to a tier system where certain skills are valued highly, and people with those skills can get a visa more quickly. In general, getting a visa is easier for those who have money to invest, or who have valuable skills, or who already have a job offer in the UK.
Becoming a UK Citizen
Once you're living in the UK, you have several different possibilities for eventually becoming a citizen or resident.
People over 18 who meet UK residency requirements can become naturalised citizens.
Citizenship can be granted to British nationals and protected persons, and spouses or civil partners of citizens. If one or both of your parents are British you may be able to apply for citizenship.
Another option is indefinite leave to remain, which you can apply for after you've been living in the UK for several years.