Cryptography is the study and practice of techniques designed to secure communication through the creation and use of encoded information. At its core, the discipline involves algorithms that transform readable data, known as plaintext, into an unreadable format called ciphertext. The mathematical principles governing this transformation ensure confidentiality, meaning that unauthorized parties cannot discern the original message. Modern cryptography relies heavily on complex mathematical structures, utilizing techniques such as symmetric-key encryption, where the same key is used for both encoding and decoding, and asymmetric-key cryptography, which employs distinct public and private keys. This field is fundamental to securing digital systems, guaranteeing data integrity, authenticity, and privacy across various technological platforms.