Security systems are gaining increasing importance in recent times to protect life and valuable resources. Many advanced methods of providing security have been developed and are in use in the last few decades. Of these, one important area is the security system required for military/strategic applications, which has advanced greatly. But, such systems being complex and expensive are useful in high-end applications only. However, with the recent progress in technology and the growing need for increased security in civilian and other applications, many low cost solutions for security systems have now emerged. As a result, many applications where only a simple intruder alarm was the means of providing security in earlier days are now able to associate with more advanced and foolproof access control techniques. And the field of Access Control Systems (ACSs) using modern approaches has become a major means of providing security in all applications, both military and civilian.