Prepared by: Asst. Lecturer Al-Batool Abdulmahdi Saleh With the rapid development of communication technologies and digital systems, data has become a primary target for cyberattacks, making encryption one of the most important means of protecting it. This article aims to review the concept of encryption, its modern types, and its effective role in protecting data from unauthorized access, while highlighting the most prominent practical applications in contemporary computer systems. The increasing reliance on computers and the Internet has led to a massive growth in the volume of exchanged data, whether personal, institutional, or governmental. This reality has imposed significant security challenges, most notably the protection of data confidentiality and integrity. Encryption is considered one of the most important techniques used to achieve information security, as it works by transforming data into an unintelligible format that can only be read by authorized parties. Concept of Encryption Encryption is the process of converting original data (plaintext) into encrypted data (ciphertext) using a mathematical algorithm and an encryption key, so that it cannot be understood without possessing the appropriate decryption key. Encryption aims to ensure: • Confidentiality: Preventing unauthorized access. • Integrity: Protecting data from alteration. • Authentication: Verifying the identity of the sender or receiver. Types of Modern Encryption Techniques . Symmetric Encryption This type relies on the use of a single key for both encryption and decryption. It is characterized by speed and efficiency and is commonly used to encrypt large volumes of data. Examples include: • AES (Advanced Encryption Standard) • DES and 3DES (although they are less commonly used today) . Asymmetric Encryption This type uses a pair of keys: a public key for encryption and a private key for decryption. It offers a high level of security but is slower than symmetric encryption. Examples include: • RSA • ECC (Elliptic Curve Cryptography) . Hash Functions Hash functions are used to convert data into a fixed-length value and cannot be reversed. They are widely used in password protection and data integrity verification. Examples include: • SHA-256 • SHA-3 The Role of Encryption in Data Protection Encryption plays a pivotal role in information security, including: • Protecting data stored in databases and devices. • Securing data during transmission across networks. • Preventing the theft of sensitive information such as passwords and financial data. • Supporting secure systems such as e-commerce and digital banking services. Applications of Modern Encryption Encryption techniques are used in many fields, including: • Secure communications (HTTPS, VPN). • Electronic payment systems. • Protecting Internet of Things (IoT) systems. • Operating system security and cloud storage protection. Future Challenges Despite the effectiveness of encryption, it faces future challenges such as: • The advancement of computing capabilities, especially quantum computing. • Secure key management. • Balancing security levels with system performance. Modern encryption techniques have proven to be an essential element in protecting data and ensuring the security of computer systems. With the continuous evolution of digital threats, it is necessary to develop more efficient and secure encryption algorithms and adopt them widely across various technological applications.