Cryptography is the study and practice of protecting information by data encoding and transformation techniques. It includes means of hiding information (such as encryption) and means of proving that information is authentic and has not been altered from its original form (such as digital signatures).
Applications of cryptography include ATM cards, computer passwords, and electronic commerce.
Cryptography is a subdiscipline of pure mathematics and computational mathematics. It is also related to computer science, information security, and electrical engineering.