The purpose of a digital signature in cybersecurity is to verify the authenticity and integrity of a digital message or document. By using cryptographic algorithms, a digital signature ensures that the sender's identity is legitimate and that the message has not been altered in transit. This adds an essential layer of security in electronic communications, often employed in legal documents and software distribution. Digital signatures provide proof of origin and non-repudiation, meaning the sender cannot later deny having sent the message, thus fostering trust in digital transactions.