Not every URL is visible so long. Many addresses do not include the file name, but simply pointing to a directory, like this: http://www.w3schools.com/ http://w3schools.com/html/ When the server receives a request for a directory name instead of a specific file, look in The directory for the default document, typically called index.html. So, in fact indirectly, we type in the full address like this (for example, if index.html as default): http://www.w3schools.com/index.html
The default file name (also referred to as the index file) can vary, and depending on how the server is configured. In this example, named index.html, but some servers use the file name default.htm. If the site uses a server-side programming to generate the page, the index file may be named index.php or index.asp. Another thing to note is that in the first instance, the original URL does not have a slash to indicate it is a directory.
When the slash is omitted, the server just add one if you find a directory with that name. Index file is also useful for security. Some servers (depending on their configuration) displays the contents of a directory if a default file is not found. One way to prevent people from seeing the files in the directory is to make sure no index file in each directory. The server administrator can also add other protection to prevent the directory displayed in the browser.
After the index file is opened by the browser, it will be presented all available information in the HTML document from the file. As an example can be seen in the following figure:
Figure 1.4. Example Web
At the top of Figure 1.4, showing a minimal web page as it appears in the browser. Although seen as a coherent page, is actually assembled from four separate files: an HTML document (index.html), a style sheet (kitchen.css), and two graphics (foods.gif and spoon.gif). HTML document will show you everything.