ChaCha20 is a widely-used symmetric encryption algorithm designed by Daniel J. Bernstein. It is known for its speed and security, making it a popular choice for various cryptographic applications. ChaCha20 operates on 256-bit blocks and supports key lengths of 128, 256, or 512 bits. It is particularly well-suited for use in scenarios where performance is crucial, such as in real-time communication protocols and disk encryption. ChaCha20 is also resistant to certain types of cryptanalytic attacks, providing strong security guarantees. Overall, ChaCha20 is a versatile and efficient encryption algorithm that is widely adopted in modern cryptographic systems.