Step 1: Understanding HTTPS.
HTTPS (HyperText Transfer Protocol Secure) is the secure version of HTTP. It encrypts communication between the client (browser) and the server.
Step 2: Role of SSL.
To enable HTTPS, websites need an SSL/TLS certificate. This certificate handles encryption and authentication, ensuring secure data transfer.
Step 3: Evaluate options.
- Search Engine Optimization: Boosts ranking but is not a prerequisite for HTTPS.
- Digital authenticity: A general concept, not a technical prerequisite.
- WWW Certificate: This type of certificate does not exist.
- SSL Digital Certificate: The correct choice, as it enables HTTPS.
Final Answer: \[\boxed{\text{SSL Digital Certificate is required for HTTPS.}}\]