HTTP, HTTPS

Don’t spell out unless you're discussing protocols or URLs, and your audience might be unfamiliar with the abbreviation. When you have a reason to spell out, use Hypertext Transfer Protocol for HTTP and Hypertext Transfer Protocol Secure for HTTPS.

Use all uppercase when referring to the HTTP or HTTPS protocol itself. In general, omit https:// and https:// from URLs. If for some reason you need to include https:// or https:// as part of a URL, use all lowercase.

See also URLs and web addresses