A digital signature serves as a virtual fingerprint in cybersecurity, providing authentication and integrity to digital messages or documents. It uses asymmetric encryption, generating a unique hash value that is encrypted with the sender's private key. This allows the recipient to verify the sender's identity using their public key and ensures that the content has not been altered during transmission. Digital signatures are crucial for ensuring the authenticity of digital communications, such as contracts and financial transactions, enhancing overall cybersecurity measures.