What is a link/URL?

From Wiki

A link or URL (Universal Resource Locator) is the unique "address" of a web page located within the Internet. It starts with htt://www and can be found on the address bar near the top of typical web browsers. You can find the URL of a web page by navigating to the web page and then copying the URL from the address bar into an email or other document.

You can find the address of web site home pages and some photo albums like Google Picasa this way. In other cases, like Facebook photo albums, you have to lookup the URL by following a procedure. I've included this procedure on the Main Page.