About URL and Local Host....

A Uniform Resource Locator (URL) is used to address a document (or other data) on the world wide web.

http - HyperText Transfer Protocol - Common web pages starts with http://. Not encrypted

https - Secure HyperText Transfer Protocol - Secure web pages. All information exchanged are encrypted

ftp - File Transfer Protocol - For downloading or uploading files to a website. Useful for domain maintenance

• host - defines the domain host (the default host for http is www)
• domain - defines the Internet domain name, like www.google.com
• port - defines the port number at the host (the default port number for http is 80) 
• path - defines a path at the server (If omitted, the document must be stored at the root directory of the web site)
• localhost path - http://localhost/