"HTTPS" signifies that a website is using HyperText Transfer Protocol Secure, which ensures a secure connection between users and the site. This protocol encrypts data, protecting it from eavesdroppers and man-in-the-middle attacks. HTTPS also boosts SEO rankings and establishes trust, as users see a padlock icon indicating a safe browsing experience. Websites utilizing HTTPS are less likely to be flagged by browsers as insecure, enhancing user confidence and overall site credibility.