Non-domicile
How you are taxed in the UK is one of the factors that relate to your domicile. If your domicile belongs to any other country but this country, you are known as non-domicile or non-dom. If you are a tax resident in the UK non-dom status gives you some benefits, like an opportunity to use remittance basis and pay your taxes only on income and gains received in the country or remitted here.
In the UK, your immigration status and tax residence are not directly related and must be considered separately. Your immigration status is your rights to enter, live and work in the country depending on your visa or nationality. Your tax residence position must be considered when arriving to the country on any type of visa.