If so, what kind of data can be communicated?
To be honest, I don't understand the question. RFID transponders (chips are only part of the device, like the CPU in a computer) are designed to communicate with a reader, so all transponders thus transmit and receive communications. The transfer of data to and from an RFID transponder is legal as long as the system operates within the frequency, power output and other regulations established for wireless devices for the particular country in which it is being used.
The information communicated is often just a serial number. In the case of a medical implant, that number is associated with medical information stored on a secure server accessible via the Internet (hopefully, the data is secure). For other types of RFID transponders, the information communicated can be a serial number plus other information, such as the store to which an item should be shipped, or the date on which an item was manufactured.
—Mark Roberti, Founder and Editor, RFID Journal