HTML and CSS

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You have probably used so-called "What-You-See-Is-What-You-Get" (WYSIWYG) web page editor before. You select text, press the bold button, and voilà! Your text is bold. But what's really happening behing the scenes is that your editor is generating HTML and CSS code. Indeed, every page you view on the internet is built using HTML and CSS. In this guide, you will learn the principles of HTML and CSS and learn how they fit together to make a web page.

Basic Structure of a Web Page

Open up a plain text editor (like Notepad on Windows or TextEdit in Plain Text mode on Mac OS X) and insert the following: 

<!DOCTYPE html>
<html>
<head>
	<title>My First Web Page</title>
</head>
<body>
	<p>Hello World!</p>
</body>
</html>

Now save the file, and open it in Firefox. You should see the following:

(image here)

What you have just produced is the bare bones of every web page on the internet. Things to notice:

  • The page begins with a DOCTYPE declaration. This is a mandatory part of a web page, and it tells the browser what version of HTML to use when rendering your page. In this case, the browser should use HTML 5.
  • The rest of the page consists of tags, in a hierarchy as follows:
    • html
      • head
        • title
      • body
        • p

Introduction to HTML

HTML stands for HyperText Markup Language. Notice that HTML is not a programming language, so it doesn't have classes, methods, variables, or anything else you may be used to seeing. Instead, HTML defines the content of a web page, and it uses tags to do that for you.

Tags

Tags define the content of your page. There are two types: content tags and empty tags.

Content Tags

A content tag is a container for other tags on your page, and it participates in the nesting hierarchy of a web page. The general format looks like this: 

<tagname> Contents </tagname>

If you've used BBCode before in online forums, HTML should look familiar, except that it uses angle brackets (less-than and greater-than signs) instead of square brackets.

Empty Tags

An empty tag represents an element on your page that does not participate in the nesting hierarchy. An empty tag looks like this: 

<tagname />

Although the trailing slash is optional on empty tags, it is considered best practice to include it, and it also makes it more clear what's a content tag and what's an empty tag when reviewing your code.

Attributes

Both content tags and empty tags can have attributes that further define their functionality. You define an attribute like this: 

<contenttag attribute="value"> Content </contenttag>
<emptytag attribute="value" />

Commonly Used Tags

Here is a list of commonly used tags in HTML. For a complete list, see the list at W3Schools.

Empty tags are distinguished from content tags by the presence of a trailing slash.

Semantic Elements

Use these tags for defining broad sections of your page with a specific purpose.

  • <header> Defines the header section of a web page
  • <footer> Defines the footer section of a web page
  • <nav> Defines the section of your page that contains navigation links
  • <article> Defines an article on your page (useful for screen readers)
  • <section> Defines a real section of your page; for example, one with unique headings distinct from the rest of the document
  • <figure> Defines a figure
    • <figcaption> Defines a caption for that figure (<figcaption> should be nested inside of <figure>)
  • <form> Defines a form into which the user should input data
    • <input type="text/number/date/radio/etcetera" name="name" /> Defines an input field of a certain type
    • <label for="input-id"> Defines a label for an input field with the ID input-id
    • <select name="name"> Defines an input field where the user can select one or more choices (like a drop-down box)
      • <option value="value"> Defines an option for the select box
    • <textarea name=""> Defines a text box (which is larger than a text field)

External Media

Use these tags to include external media onto your page.

  • <iframe src="source"> Represents a little window on your page into which source is loaded; source could be a PDF document, for example, or an entire other web page
  • <link rel="what" type="mime" href="source" /> Defines an external document what located at source with the mime type mime that should be loaded into your HTML page. Note: <link /> does NOT define a hyperlink! <a> is for that. Used most commonly for including CSS stylesheets.
  • <img src="source" alt="text" /> Defines an image located at source that has a textual representation of text
  • <audio> Represents an audio clip on your page
  • <video> Represents a video clip on your web page
  • <canvas> Defines a canvas for advanced drawing (we will learn more about this in future modules)

Outlining Elements

Use these elements to define an outline for your page, including definitions and citations.

  • to

    Defines the outline for your page

    • Defines a paragraph of text

    • Defines a Dictionary List
      • Defines a Dictionary Term
      • Defines a Dictionary Definition
    • Defines a table for displaying data
      • <thead>, <tbody>, <tfoot> Defines the heading, body content, and footing of a table
      Defines a table row
      Defines a table cell that contains a heading
      		• Defines a table cell that contains data
      • and
          Define ordered and unordered lists, respectively (meaning numbered lists and bulleted lists)
          • Defines a list item for either
              or
              • Represents a short, inline quotation quoted from another source

              • Represents a longer block of text quoted from another source

            Miscellaneous Elements

            This section lists useful elements that don't fit into one of the other categories.

            • <a href="destination"> Make a hyperlink to destination

            •  Denotes where a line break should appear (note that white space is ignored when rendering, so a line break in the source code is not reflected in the output)
            • <button> Defines a clickable button
            • Defines a piece of computer code
            • <output> Defines the result of a calculation
            •  Defines pre-formatted text in which whitespace will be preserved
            * <script> Defines a script for your page (we will learn a lot more about this in later modules) *
            Defines a block section of your document (useful for styling) * Defines an inline section of your document (useful for styling)

            High School Analogy

            In more ways than not, HTML can be thought of as a markup language for five-paragraph essays that you wrote in history class in high school.

            is used to denote long quotations;

            through
            denote the outline;

            denotes new paragraphs; <figure> and <figcaption> represent exhibits; <section> could represent chapters if you were writing a longer report; and so on. Take home message: HTML defines the content of your page. Use it to its full ability.

            Introduction to CSS

            Notice that we haven't said a word about how things look yet. This is because that is what CSS is for!

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