Illinois Summons (Day Certain) is a document issued by the court ordering a person to appear in court on the date specified. It is typically issued by a judge or the clerk of the court after a lawsuit has been filed, and is used to notify a defendant of an upcoming court hearing. This summons is typically served in person by a sheriff or process server. There are two types of Illinois Summons (Day Certain): a summons for a defendant to appear in court and a summons for a witness to appear in court. Both types of summons include the date, time, and location of the court hearing, as well as the name of the court and the name of the plaintiff and defendant.