These are helper applications that the browser will call when it sees a file with a particular extention. The use of these plug-ins has allowed web site developers to be much more creative and imaginative with their pages. A home page is similar to a table of contents in a book. It is the starting point or page that displays when you first access a site. It is sometimes explained by comparing it to a root directory in DOS with links to its subdirectories and also to other different directories.
Home pages can contain anywhere from a few to a few hundred links to other pages.
Uniform Resource Locator. This is the addressing system used by the World Wide Web. It describes the location of a file or server anywhere on the internet. On the Internet there are many protocols . These are the 'rules and regulations' that help to maintain the ease with which computers 'talk' to each other.