A TLS certificate fingerprint is a short, unique string derived from a cryptographic hash of a website’s TLS certificate. It acts as a digital identifier for the certificate, allowing security tools and professionals to verify the authenticity of the certificate presented by a server. By comparing fingerprints, it is possible to detect if a certificate has been tampered with or replaced, which is crucial for identifying man-in-the-middle attacks or tracking malicious infrastructure that reuses certificates across multiple domains. Fingerprints are commonly represented as hexadecimal strings and are used in threat intelligence to correlate related malicious activities.