A digital signature serves as a security mechanism in cybersecurity, verifying the authenticity and integrity of digital messages or documents. It uses cryptographic techniques to provide assurance that a message originates from a specific sender and has not been altered in transit. Digital signatures are crucial for securing communications and transactions in e-commerce, electronic contracts, and software distribution. By confirming both the sender's identity and the content's legitimacy, digital signatures help build trust in online interactions and comply with legal and regulatory requirements, thus enhancing overall cybersecurity measures.