The term 'digital signature' in cybersecurity signifies a cryptographic technique used to validate the authenticity and integrity of digital messages or documents. Digital signatures leverage public key infrastructure (PKI) to generate a unique signature that is attached to a document or message. This ensures that the sender cannot deny having sent the message, establishing non-repudiation. Digital signatures are critical for secure communications, enabling scenarios like e-signatures in contracts, verifying software distributions, and ensuring data integrity in electronic transactions.