As well as income tax being taken from your salary, payroll will also deduct National Insurance contributions. The company has to pay National Insurance contributions for you as well.
You pay National Insurance contributions to build up your entitlement to social security benefits which are provided in certain events such as unemployment, sickness or other incapacity, maternity, and retirement. Each of these benefits has its own different qualifying conditions, which must be satisfied before payment can be made.
You stop paying National Insurance contributions in the year you reach State Pension age.