Encryption is a security technique that transforms readable data, known as plaintext, into an unreadable format called ciphertext using a specific algorithm and an encryption key. This process ensures that only authorized parties with the correct decryption key can access the original information. Encryption is widely used to protect sensitive data during storage and transmission, safeguarding it from unauthorized access, cyberattacks, and data breaches. Common applications include securing online communications, financial transactions, and personal information.