Step 1: Understanding HTTPS.
HTTPS (HyperText Transfer Protocol Secure) is the secure version of HTTP. It encrypts communication between client (browser) and server.
Step 2: Role of SSL.
To enable HTTPS, websites require an SSL/TLS certificate. This certificate provides encryption and authentication, ensuring secure data transfer.
Step 3: Evaluate options.
- Search Engine Optimization: Improves ranking but not required for HTTPS.
- Digital authenticity: A broad concept, not the technical requirement.
- WWW Certificate: No such specific certificate exists.
- SSL Digital Certificate: Correct, as it establishes HTTPS.
Final Answer:
\[
\boxed{\text{SSL Digital Certificate is required for HTTPS.}}
\]