The basic components of RFID system is,

RFID Tags:
Chip tags consist of a microchip usually attached to physical objects and store a unique identification for the object that they are attached to. In addition, they might store some other data..

RFID tag is a microchip combined with an antenna in a compact package, the packaging is structured to allow the RFID tag to be attached to an object to be tracked.

The tag's antenna picks up signals from an RFID reader or scanner and then returns the signal, usually with some additional data (like a unique serial number or other customized information).

RFID tags can be very small - the size of a large rice grain. Others may be the size of a small paperback book.

There are two types of tags, Active RFID tag and Passive RFID tag (Some time you could find a 3rd type called Semi Passive RFID tag)  

RFID Readers features

• Readers read/write data from/to tags via an antenna
• Come in various forms
• Have input/output ports
• Usually support multiple protocols (EPC, ISO)
• Communicate over the network with a host
• Perform anti-collision, filtering, reader management functions
• Come in various forms, such as fixed, mobile and handheld.

RFID Software

• Tag data read by RFID hardware must be provided to applications running business processes
• Software to accomplish this is divided into three layers: 
   - Device Management 
   - Middleware
   - Enterprise Applications