Final answer:
Users can be assured they are on a retailer's authentic website by checking for a Digital Certificate, which verifies the site's security. SSL, a type of Digital Certificate, encrypts communication to protect sensitive information.
Step-by-step explanation:
One key aspect to ensure that users are on a retailer's authentic website and not an imposter's look-alike site when entering credit card details is by checking for a Digital Certificate. A Digital Certificate serves as an assurance that the website is verified and secure, as it is issued by a trusted certificate authority. Unlike a Digital Signature, which validates the integrity of the data, or a Hash Digest, which ensures data has not been tampered with, the Digital Certificate ensures the legitimacy of the website. One common type of Digital Certificate implementation is the use of SSL (Secure Socket Layer), which encrypts the communication between the user's browser and the website, making it safe to transmit sensitive information like credit card details.