An International Driver’s License is a requirement in most countries to rent and drive vehicles legally.
If you have a car rental reserved in a foreign country– you will most likely be asked to present an International Driver’s License.
An International Driver’s License is a UN regulated document that tells rental agencies and foreign authorities that you are the legal holder of a valid driver’s license from your home country.
Please refer to the link for more details: https://www.e-ita.org