High Frequency RFID operates at 13.56Mhz.
HF is an inferior protocol to UHF and is covered only for completeness. Today, there are reasons to select HF in a project; however, these reasons are slowly disappearing and commercial-off-the-shelf UHF solutions are replacing them.
HF Pros
Low Cost RFID Readers.
Many manufacturers and a well developed ISO standard.
Good near water.
Large data storage options.
HF Cons
Slow RF signaling protocol making it difficult to handle many RFID tags in a short time.
Short Tag Read Range (< 3 feet).
Expensive Tags, typically over $1 USD each. Due to complexity and copper used in HF tags, it would be more difficult to make these tags inexpensive.