Bitcoin transactions are secured by cryptography, which is a method of encryption. Cryptography is the practice and study of techniques for secure communication in the presence of third parties. Cryptography uses advanced mathematical algorithms to ensure that data is transmitted securely and that only authorized users can access the data. Cryptography is also used to verify the authenticity of the sender and receiver of a transaction, as well as to protect the integrity of the data itself.

Cryptography has become an essential part of the digital world and is used in everything from banking and finance to social media and email. Bitcoin transactions use cryptographic algorithms to ensure that the data is transmitted securely and that only the intended recipient can access it. By using cryptography, Bitcoin transactions are secure and immutable, meaning that they cannot be altered or reversed without the consent of all participants.