Illinois Stalking laws 720 ILCS sec.12-7.3
Illinois Harassing and Obscene Communications Act ...... summary
Chapter 720 Criminal Offenses 720 ILCS 135
Harassment doesn’t only occur face-to-face but can also occur over the phone or internet. A first offense harassment conviction is a Class B Misdemeanor and carries a possible sentence of up to 6 months in jail and/or a fine of up to $2,500.
If you have already been convicted of harassment and are convicted again, the second is a Class A Misdemeanor which carries a possible sentence of up to one year in jail and a fine of up to $2,500.
If you are facing a serious criminal charge like stalking or harassment, you need someone on your side to help you try to fix this legal problem.
There are also certain circumstances where a harassment conviction can be a Class 4 Felony
Harrassment can refer to many different types of conduct and potentially fall within the purview of several different criminal statutes. More information is needed to adequately address your concerns. If you are the victim, contact the police and let them decide what, if any, crimes have been committed. If you are the accused, contact an experienced criminal defense attorney before you are questioned or charged. Most of us provide free consultations. www.galivanlaw.net
If you didn't find it under the statute cited by Mr. Brinkmeier it may be because it was repealed as they continue to update and "simplify" the Illinois Criminal Code. Effective 1/1/13 it will be found at 720 ILCS 5/26.5-0.1 and the parts that follow. A link is contained below.
However, as Mr. Galivan pointed out, you may have a broader or narrower idea of "harassment" does than the law says. Therefore, I agree with him that if you are the victim you may speak with the police or the State's Attorney. If you are concerned with being charged yourself, then consult with an experienced criminal defense (or juvenile defender if you are under 17) as many more facts would need to be known.
This answer is provided for informational purposes only and does not create an attorney-client relationship. Follow-up with a licensed attorney who regularly practices in this field is strongly recommended.