Abstract-RFID (Radio Frequency IDentification) technology has moved from academic obscurity into mainstream business and practice. Although this technology has many catching and exclusive characteristics, security and privacy issues associated are not easy to address due to tags' modest computational and storage capabilities and the necessity to keep their prices low. This paper provides a general overview of the rather broad area of RFID security and privacy and gives the main citations for the comprehensive understanding and further explorations of this area. To be specific, previous attempts to enable or increase the security and privacy of the low-cost RFID systems are examined, including: (1) design and cryptanalysis of lightweight ciphers; (2) privacy-preserving authentication protocols and their designing requirements; and (3) non-conventional solutions leveraging physical characteristics of RFID tags or physical layer of the tag-reader communication for security and privacy purposes.