This session deals with some important cryptographic terms that are required to fully understand some of our future sessions that cover cryptographic network protocols like ssh, ftps and https. The major terms discussed are encoding, hashing and symmetric encryption. The famous Linux tool openssl is used for calculating different hashes. Two uses of hashing are also discussed, i.e., storing passwords and ensuring data integrity. Finally, a practical hands-on example is used to understand symmetric encryption on a Linux terminal.