Hashing is a process used in computer science to convert input data of any size into a fixed-size string of characters, which typically represents the data in a compressed format. The output, known as a hash value or hash code, is produced by a hash function and is designed to uniquely represent the original data. Hash functions are deterministic, meaning the same input will always produce the same output, but they are also designed to be fast and efficient, making them suitable for a variety of applications, such as data retrieval, password storage, and digital signatures.

In security contexts, hashing is often used to protect sensitive information, such as passwords. Instead of storing passwords in plaintext, systems store their hash values, which makes it difficult for attackers to recover the original passwords even if they gain access to the hashed data. However, hashing alone is not sufficient for security, as attackers can use techniques like brute force or rainbow tables to reverse-engineer the original data. To mitigate this, cryptographic hash functions, such as SHA-256, are used in conjunction with techniques like salting, where a random value is added to the input before hashing. Hashing also plays a crucial role in data integrity, ensuring that transmitted or stored data has not been tampered with.