A digital certificate serves as a security mechanism to verify the identity of individuals, organizations, or devices in online transactions. Issued by trusted entities known as Certificate Authorities (CAs), these certificates contain essential identification information and a public key. Digital certificates establish a secure connection over networks by enabling encryption and authentication. When a user connects to a website, the browser checks the digital certificate to confirm the site's legitimacy, thereby protecting against fraud and man-in-the-middle attacks. Overall, digital certificates are vital for establishing trust in online communications.