Biometric is a unique, measurable physiological or behavioral characteristic of a person. The biometric system is one such that can provide accurate and reliable scheme for person verification and authentication. Unimodal biometric systems have to contend with a variety of problems such as noisy data, intra-class variations, restricted degrees of freedom, non universality, spoof attacks, and unacceptable error rates. Several of these problems can be addressed by deploying multimodal biometric systems that combine two or more biometric modalities. By combining multiple sources of information, these systems improve matching performance, increase population coverage, deter spoofing, and facilitate indexing. Different scenarios and fusion levels are possible and different integration strategies can be adopted to consolidate information in multi modal systems.