Automatic Speaker Verification (ASV) systems are being used for biometric authentication even if their vulnerability to spoofing is widely acknowledged. Recent work has proposed different spoofing approaches which can be used to test vulnerabilities. A tutorial of the design and development of ASV is presented. ASV is the use of a machine to recognize a person from a spoken phrase. These systems can operate in two modes: to identify a particular person or to claim a person's claimed identity. Speech recognition and the basic components of Automatic Speaker Recognition systems are shown and design tradeoffs are discussed.