What are the requirements for AirDrop?

Could you please elaborate on the prerequisites for AirDrop? I'm curious to know what specific conditions need to be met in order to utilize this feature effectively. Are there any specific device requirements, such as certain models or operating system versions? Also, do both devices need to be connected to the same Wi-Fi network or Bluetooth for AirDrop to work? Additionally, are there any privacy or security considerations that users should be aware of when using AirDrop? I'm interested in understanding the full scope of the requirements to ensure a smooth and secure experience.