The significance of a digital certificate lies in its role in establishing secure connections over the internet, often within the context of HTTPS. Digital certificates authenticate the identity of a website or entity, ensuring that communication between the user and the server is encrypted and secure. They use public key infrastructure (PKI) to manage keys and verify identities. This strengthens trust, allowing users to engage in online transactions confidently. Without digital certificates, sensitive data like credit card information could be vulnerable to interception and fraud.