Biometrics is the science and technology of measuring and analyzing biological data of human body for increasing systems security by providing accurate and reliable patterns and algorithms for person verification and identification and its solutions are widely used in governments, military and industries. Single source of information in biometric systems are called unimodal systems and are perfect but they often suffer from some problems when they face with noisy data such as: intra-class variations, restricted degrees of freedom, spoof attacks and non-universality.
Several of these problems can be solved by using multimodal biometric systems that combine two or more biometric modalities. Various methods, fusion levels and integration strategies can be applied to combine information in multimodal systems.