Infrared communication (IrDA) transfers data over short distances (tens of cm to 1m) using infrared light. Standard on Japanese feature phones, it was widely used for contact exchange, photo sharing, and business card transfer.
Usage involved pointing two devices' infrared ports (typically on top) at each other and operating both. "I'll send my contact via infrared" was everyday 2000s Japan. It was the go-to method for exchanging numbers at social gatherings.
Technical characteristics include high directionality (devices must face each other) and relatively low speed (max ~4Mbps). Compared to Bluetooth, it required no pairing but couldn't work through obstacles.
Smartphones eliminated infrared communication. Contact exchange shifted to LINE QR codes, and data transfer to AirDrop, Bluetooth, and cloud services. Virtually no current smartphones support infrared. See telephone evolution for communication technology transitions.