Encryption is one of the most fundamental tools in data protection. It transforms readable data into ciphertext that can only be interpreted with the correct decryption key. Encryption is applied to data in transit (e.g., HTTPS traffic), at rest (e.g., encrypted hard drives), and in use (emerging through confidential computing). Symmetric encryption (like the AES algorithm) uses the same key for both encryption and decryption, while asymmetric encryption (like the RSA algorithm) uses public-private key pairs and is essential for secure communications and authentication. They will be explained in more detail in the future.