735 ILCS 5/9-210
When default is made in any of the terms of a lease, it is not necessary to give more than 10 days' notice to quit, or of the termination of such tenancy, and the same may be terminated on giving such notice to quit at any time after such default in any of the terms of such lease. Such notice may be substantially in the following form:
"To A.B.: You are hereby notified that in consequence of your default in (here insert the character of the default) of the premises now occupied by you, being, etc., (here describe the premises) I have elected to terminate your lease, and you are hereby notified to quit and deliver up possession of the same to me within 10 days of this date (dated, etc.)."
The notice is to be signed by the lessor or his or her agent, and no other notice or demand of possession or termination of such tenancy is necessary.
735 ILCS 5/9-210