The National Instant Criminal Background Check System, or NICS, is a system used in the United States to determine if a person is eligible to purchase firearms. Established in 1998, it checks the backgrounds of individuals against various databases to identify any criminal history, mental health issues, or other disqualifying factors. When someone attempts to buy a gun from a licensed dealer, the dealer contacts NICS to initiate a background check. The system provides a response within minutes, allowing for a quick decision on the sale. This process aims to enhance public safety by preventing firearms from being sold to individuals who may pose a risk.