Sealed vs. expunged
A sealed record still exists but can only be viewed by law enforcement or through a court order. In general, sealed records are not public information and aren't available to employers, for example. An expunged record is completely erased.
What can be sealed
You may be able to get a record sealed if you were released without a conviction, if the conviction is reversed, if you are sentenced to supervision after a misdemeanor (and you have no felony or misdemeanor convictions in the past three years) or if you were convicted but there is no conviction for a felony or misdemeanor, and you have not received court supervision, for the past four years.
What cannot be sealed
Most felonies cannot be sealed, with the exception of Class 4 drug possession or prostitution cases. DUIs cannot be sealed. Article 11 cases (adultery, fornication, public indecency, obscenity, marrying a bigamist) cannot be sealed. You also can't seal records of assault, aggravated assault, battery, domestic battery, violation of an order of protection, criminal sexual abuse, or sex offender registration offenses. Dog fighting and inhuman treatment of animals fall into this category as well.
What can be expunged
You may be able to get your record expunged if there was no conviction. You can get expungement in some cases if you get a pardon from the governor that specifically includes expungement. If you received supervision for a first-time drug or alcohol offense, and the supervision ended five years ago or more, you may be able to get the record expunged. If you received supervision for having an uninsured vehicle, for suspended registration for non-insurance, or displaying false insurance, and the supervision was terminated five years ago or more, you may be able to get it expunged. Supervision for domestic battery, criminal sexual abuse, aggravated battery of a child and retail theft work the same way.
What cannot be expunged
If you are found guilty of a drug or alcohol violation and get a sentence other than probation, your record cannot be expunged. Cases ending in DUI supervision cannot be expunged. Sexual offense cases against a minor, regardless of whether it ended with supervision or a conviction also cannot be expunged, nor can conditional discharges.