730 ILCS 5/5-4.5-85

(a) FELONY. The particular classification of each felony is specified in the law defining the felony. Any unclassified offense that is declared by law to be a felony or that provides a sentence to a term of imprisonment for one year or more is a Class 4 felony. (b) MISDEMEANOR. The particular classification of each misdemeanor is specified in the law or ordinance defining the misdemeanor. (1) Any offense not so classified that provides a sentence to a term of imprisonment of less than one year but in excess of 6 months is a Class A misdemeanor. (2) Any offense not so classified that provides a sentence to a term of imprisonment of 6 months or less but in excess of 30 days is a Class B misdemeanor. (3) Any offense not so classified that provides a sentence to a term of imprisonment of 30 days or less is a Class C misdemeanor. (c) PETTY OR BUSINESS OFFENSE. Any unclassified offense that does not provide for a sentence of imprisonment is a petty offense or a business offense.