NFC (Near Field Communication) technology requires devices to be within 6 inches (15.24 cm) of each other to communicate. This short range facilitates secure communications for tasks such as contactless payments, quick data transfers, and connection setups between devices.
Reference:
In the sections dealing with wireless technologies and data exchange methods, CompTIA IT Fundamentals documentation outlines the operational characteristics of NFC, including its very limited range, which supports its use for secure, close-proximity communications.