Section 720 ILCS 5/10‑1 of the Illinois Revised Statutes has defined Kidnapping as:

(a) … when a person knowingly:
(1) And secretly confines another against his will, or
(2) By force or threat of imminent force carries another from one place to another with intent secretly to confine him against his will, or
(3) By deceit or enticement induces another to go from one place to another with intent secretly to confine him against his will.
(b) Confinement of a child under the age of 13 years is against his will within the meaning of this Section if such confinement is without the consent of his parent or legal guardian.
(c) Sentence.
Kidnapping is a Class 2 felony.

Section 720 ILCS 5/10‑3 of the Illinois Revised Statutes has defined Unlawful Restraint as:

(a) A person commits the offense of unlawful restraint when he knowingly without legal authority detains another.
(b) Sentence.
Unlawful restraint is a Class 4 felony.

Section 720 ILCS 5/10‑4 of the Illinois Revised Statutes has defined Forcible Detention as:

(a) A person commits the offense of forcible detention when he holds an individual hostage without lawful authority for the purpose of obtaining performance by a third person of demands made by the person holding the hostage, and
(1) the person holding the hostage is armed with a dangerous weapon as defined in Section 33A‑1 of this Code, or
(2) the hostage is known to the person holding him to be a peace officer or a correctional employee engaged in the performance of his official duties.
(b) Forcible detention is a Class 2 felony.