Curve25519 is a modern elliptic-curve cryptography (ECC) algorithm designed for fast, secure, and efficient key exchange. Developed by Daniel J. Bernstein in 2005, it is widely used in protocols like TLS, SSH, and Signal for establishing shared secrets over insecure channels. Curve25519 offers strong security properties, resistance to common cryptographic attacks, and high performance on a variety of hardware platforms. Its design aims to avoid common implementation pitfalls, such as side-channel attacks, making it a preferred choice for secure communications. Curve25519 operates over a prime field with a 255-bit key size, balancing security and computational efficiency.