Reader/Writer is an NFC mode for hardware that describes when an active NFC device interacts with a passive NFC tag. Often the NFC device is a mobile phone or a desktop connected NFC device. The NFC device detects the presence of the NFC tag in the RF field, initiates a connection to the tag, calls a set of NFC chip commands to perform NFC operation. When the NFC tag is removed from the RF field the tag resets back to its default state. This is the most commonly used NFC mode for Connected Things projects.