When you buy something online, your credit card number travels across the internet. Encryption is the process of converting data into a code to prevent unauthorized access. It scrambles the data so that only someone with the key can read it. Without encryption, every password and message would be visible to anyone who intercepts it.

Encryption has been used for centuries. Julius Caesar shifted letters by three positions to hide military messages. Modern encryption uses mathematics. AES, the standard used by governments and banks, would take billions of years to break by brute force with today's computers.

Types of encryption

• Symmetric: same key for encryption and decryption
• Asymmetric: public key encrypts, private key decrypts
• Hashing: one-way transformation, not reversible
• End-to-end: only sender and receiver hold keys

Encryption is not just for spies. It protects your messages, your banking, your medical records, and your identity. Governments sometimes want backdoors. Security experts say backdoors weaken everyone's security. The debate is ongoing.