What is signing?

Signing, in a technological context, broadly refers to the process of digitally adding a unique identifier to data (e.g., a document, message, or piece of code) to ensure its authenticity and integrity. This identifier, called a digital signature, is created using cryptography, typically involving a private key held by the signer and a corresponding public key that can be used by others to verify the signature. Common uses include verifying the sender of an email, ensuring the integrity of software downloads, and authenticating electronic documents. In summary, it's a mechanism for non-repudiation, authentication, and integrity.