735 ILCS 5/6-141
Notice of any adverse claim or title to the land within the meaning of this Article is to be given by bringing an action for the same, by the one or the other of the parties, and may hereafter be given by bringing an action, as above provided, or by delivering an attested copy of the entry, survey or patent, from which he or she derives his or her title or claim, or leaving any such copy with the party or the spouse of such party. Notice given by the delivery of an attested copy, as above set out, is void, unless an action is filed within one year thereafter. In no case shall the proprietor of the better title be obliged to pay to the occupying claimant, for improvements made after notice, more than what is equal to the rents and profits above set forth.
735 ILCS 5/6-141