To legally carry a gun in Illinois, you must have a FOID card. This is a requirement for most people in the state, but there are exemptions.
The Illinois State Police explain that you also must meet specific requirements to be eligible to get a FOID card.
FOID card explained
The FOID acronym stands for Firearm Owner’s Identification. The requirement for gun owners to have this card is in the FOID act of 1968. Every person who wants to own or buy firearms or ammunition must have this ID.
To be eligible to get a FOID card, you must be at least 21 years old. If you are under that age, a legal guardian must sponsor you. You also cannot otherwise have a penalty against you preventing you from possessing a firearm. For example, if you have a felony conviction or a restraining order against you, then you cannot legally possess guns.
You also cannot have a mental health issue within the last five years or have an addiction to drugs. You cannot be intellectually disabled, and you must be a US citizen. You can not have any violent criminal convictions within the past five years and no domestic violence charges on your record.
You must be a resident of the state, and you cannot have a dishonorable discharge from the military.
Most people will need to secure a FOID card. However, law enforcement, members of the military, federal officials, nonresident hunters or those at police firing ranges, and nonresidents who have their firearm in an enclosed space are all exempt from having to get the card.