Multimodal biometric system is the combination of more than one biometric trait to authenticate an individual. Unimodal biometric systems use only one biometric trait (iris, retina, face, hand geometry, fingerprint, voice, gait, signature etc.) to recognize individual. Unimodal biometric system have some limitations over authentication like noise in sensed data, intra-class variation, inter-class variations, distinctiveness, spoof attacks etc. Therefore unimodal biometric system is less secure and less reliable and this is the reason that unimodal biometric systems are become less acceptable where high security required.