Cryptography is the practice and study of techniques for securing communication and information by transforming it into a format that is unreadable to unauthorized users. It involves creating codes and ciphers to protect data from eavesdropping, tampering, or forgery.

Here are some key aspects:

1. Confidentiality: Ensures that information is only accessible to those who are authorized to see it. This is often achieved through encryption, which transforms readable data (plaintext) into an unreadable format (ciphertext).
2. Integrity: Ensures that the information has not been altered in transit. Hash functions are often used to verify the integrity of data.
3. Authentication: Confirms the identity of the parties involved in communication. This can be done through digital signatures and certificates.
4. Non-repudiation: Ensures that a sender cannot deny sending a message, providing proof of the origin and integrity of the data.

Types of Cryptography:

• Symmetric Key Cryptography: Uses the same key for both encryption and decryption.
• Asymmetric Key Cryptography: Uses a pair of keys (public and private) for encryption and decryption, enhancing security.

Applications: Cryptography is used in various applications, including secure communications (like SSL/TLS for websites), digital currencies (like Bitcoin), secure email, and many forms of data protection.

Overall, cryptography is essential for protecting sensitive information in our increasingly digital world.