Contrary to Tina Turner, frequency like love has everything to do with it.  RFID technologies operate at many frequencies, but I will only cover the most common passive ones here:  low-frequency (125 MHz), high-frequency (13.56 MHz) and ultra high-frequency (860-960 MHz).

Low-frequency (LF) passive solutions operate around 125 MHz, use less power and are less susceptible to liquids.  Read ranges are in inches.

High-frequency (HF) passive RFID solutions operate around 13.56 MHz, use more power and are less susceptible to metals.  Read ranges are at most a few feet.

Ultra-high-frequency (UHF) passive RFID solutions operate between 860-960 MHz (depending on the country), uses the most power of the three and are less likely to pass through materials.  The data transfer rate is faster than LF and HF and the read ranges can be as high as 30 feet or more.

As you can see, frequency plays a role in determining the read range of a solution.  Next time I will continue with the role the reader and antennas play.