An International Driving Permit is a supplementary document that you can obtain in addition to your national driving licence.
This means: The supplementary document is only valid in conjunction with your regular driving licence.
An International Driving Permit makes it easier for police officers abroad to check your driving licence. However, only in a small number of countries are you legally obliged to carry an International Driving Permit when driving. It is, however, recommended in some countries like the USA and South Africa in order to avoid red tape and lengthy discussions with the authorities.
Important: Always observe the rental conditions, regardless of the country-specific regulations. If a rental company requires an International Driving Permit, you must present it in order to rent the vehicle.