The State of Illinois has a law that prohibits the operation of a motor vehicle anywhere in Illinois while under the influence of alcohol, other drugs and intoxicants. This Illinois DUI law currently applies only to land vehicles other than snowmobiles and bicycles. 625 ILCS 5/1-217
It is necessary to understand that a DUI arrest involves two different categories of consequences. A DUI conviction can result in criminal penalties.
Criminal penalties involve anything that deprives a person of life, liberty or property. In essence, if a DUI conviction can lead to fines, penalties or incarceration, it is a criminal offense in which the prosecutor must prove the accused is guilty beyond a reasonable doubt. Even court supervision, while not exposing an accused to jail, can result in fines and other monetary penalties.
A conviction for DUI will cause a revocation (nullification) of your driver's license. Having it restored requires you to prove to the Secretary of State at a hearing that you will not drive drunk in the future. It's more complicated than it appears but the process examines whether or not you can be a "safe and responsible driver".
A "suspension" is a less severe form of driver's license sanction. A suspension puts your driver's license on hold temporarily. As long as your license is otherwise valid, you pay a fee at the end of the suspension and your license is returned to you without a hearing.