Czech Birth Number (rodné číslo) is a personal identifier composed of 10-digit numbers, showing the date of birth and the sex of the person it belongs to. Is not obligatory for foreigners to have a birth number though it is highly recommended since it is often required, for example, by banks when opening a bank account, or by the Registry of motor vehicles when registering a new car. Similarly, it is used as the insurance number for both health insurance and social security and taxes.