Biometrics are used to identify the identity of an input sample when compared to a template, used in cases to identify specific people by certain characteristics.

• possession-based: using one specific "token" such as a security tag or a card
• knowledge-based :the use of a code or password.
  

  Standard validation systems often use multiple inputs of samples for sufficient validation, such as particular characteristics of the sample. This intends to enhance security as multiple different samples are required such as security tags and codes and sample dimensions

  • Uniqueness- is how well the biometric separates individually from another.
  • Permanence- measures how well a biometric resists aging.
  • Collectability- ease of acquisition for measurement.
  • Performance- accuracy, speed, and robustness of technology used.
  • Acceptability- degree of approval of a technology.
  • Circumvention- ease of use of a substitute.
    
    Wikipedia