This is considered the most serious type of felony. The minimum prison term for Class X felonies is six years; the maximum is 30. There can also be a fine of up to $25,000. In some cases there are aggravating factors, which are circumstances that increase the level of a crime. For example, criminal sexual assault is a Class 1 felony, but aggravated criminal sexual assault is a Class X felony.
The punishment for Class 1 felonies is four to 15 years in prison and up to $25,000 in fines. Examples are criminal sexual assault, possession of some types of drugs (heroin, cocaine), and theft in the amount of $10,000 to $100,000.
A Class 2 felony is punishable by three to seven years in prison and fines up to $25,000. Class 2 felonies include arson, and some drug possession (2000 grams but not more than 5000 grams of marijuana), as well as theft of $2,000 to $10,000.
Class 3 felonies carry a prison sentence of two to five years, as well as the $25,000 in possible fines. Examples are aggravated battery, and theft (between $300 and $2,000).
Class 4 felonies are considered the least serious and carry a minimum prison term of one year. Class 4 felonies include aggravated assault, stalking, and some drug possession (30 grams but less than 500 grams of marijuana), and felony DUI.