Hashing is a cryptographic technique that converts data into fixed-size strings of characters, known as hashes, which serve as digital passports for data. It's used to organize and protect data, with hash codes acting like fingerprint smudges on online files. Every fixed-length hash is unique to the data it represents, ensuring data integrity and authentication. Hashing plays a crucial role in various applications such as password security, digital signatures, file verification, blockchain technology, and search engine databases.