HTML is, pretty much, the language in which the Web is written. With the help of special markups called tags, it's possible to add meaning and context to plain text, turning it into HTML. For us, HTML is a means to an end. So, if you want to learn more about it, please open http://www.w3schools.com/html/ in your preferred browser. We are not covering HTML syntax fully, nor all the beautiful magic involved in the process.

Although we will not cover HTML extensively, we will cover HTML specifically; by this, I refer to the <form> tag. Here is the deal: every time you open a webpage and there are a few blank fields for you to fill in, you're most likely filling in an HTML form. That's the plainest way to transfer data from your browser to a server. How does that work? Let's see an example:

<!-- example 1 -->
<form method='post' action='.'>
<input type='text' name='username' />
<input type='password' name='passwd' />
<input type...