If you want to quickly send photos and videos to nearby iPhones and Macs, AirDrop is the way to go. If you are a person who allows you to receive AirDrop, just tap the button displayed on the screen to select the destination, no hassle.
And AirDrop does not consume packets. Data is sent and received directly between devices and does not go through the Internet. So even when the iPhone is out of range, you can send and receive even when communication is restricted due to excessive use of packets. Sending photos via e-mail or SNS service will incur packet charges, but AirDrop does not have to worry.
That said, you may be worried when you're not connected to a Wi-Fi access point. If the Wi-Fi antenna is not displayed, the fan-shaped mark is not displayed on the status bar, and instead it is displayed as "4G" or "LTE", it is reasonable.
Still, AirDrop does not generate packet charges. This is because AirDrop performs peer-to-peer (one-to-one) communication using IPv6. Establish a session with the file destination using Bluetooth LE with low power consumption, and when transmitting a large amount of information such as a photo, route to Wi-Fi (network interface called Apple Wireless Direct Link). Switch to continue communication. It is not a specification that data is going to the Internet.
Even if Wi-Fi is turned off in Control Center (color changes to gray), Wi-Fi is not completely disabled. Since iOS 11, the Wi-Fi and Bluetooth buttons in the Control Center will only temporarily disconnect connected Wi-Fi networks and Bluetooth accessories. Therefore, even if the Wi-Fi fan-shaped mark is not displayed, the Wi-Fi communication function itself is effective and does not affect the use of AirDrop.