/>
And please remember that capitalization often matters for folder and file names - just not the server name.

Index.htm(l)
What happens if someone just enters "www.MyWebServerName.com/FolderA"? The default action is for the web server to try to list the contents (all the files) of FolderA! That is, unless you have an index.html file inside FolderA - the index.html is shown by default if no other page was specified. To restate: when a server is asked to go to a folder or directory where no file name is given, if it finds an "index.html" file there, it will put that index.html page up. Otherwise, the web server will try to list the contents of the folder or directory. (Sometimes, if preset/programmed not to do this, it will just give an error instead - this is now very common on big commercial servers.)

A useful thing to know is that, because index.html is put up automatically, this is usually why you usually don't have to type in anything after "www.ServerName.com" or "www.ServerName.com/FolderName" - the server handles finding the appropriate default file for you. And this is why so many files are named "index.html."

(Minor trivia: technically every folder or directory should end in "/" including the web server name itself - so when you see "www.cnn.com/" or "www.mit.edu/people/rei/" this is actually correct etiquette. Hardly anyone does this, though.)

HTTP://
And you've probably seen "http://" ... well, that icky-looking "http"