Blowfish is a symmetric-key block cipher designed by Bruce Schneier in 1993. It is known for its speed and effectiveness in encrypting data. Blowfish uses a variable-length key, ranging from 32 bits to 448 bits, making it flexible for different security needs. The algorithm processes data in 64-bit blocks and is widely used in various applications, including file encryption and secure communications. Due to its strong security features, Blowfish has been a popular choice for many software applications. However, it has been largely replaced by more advanced algorithms like AES (Advanced Encryption Standard) for new systems. Despite this, Blowfish remains relevant in legacy systems and certain niche applications.