Basics of HTML

Introduction

HTML (Hypertext Markup Language) is the code that is used to structure a web page and its content. For example, content could be structured within a set of paragraphs, a list of bulleted points, or using images and data tables. As the title suggests, this article will give you a basic understanding of HTML and its functions.

So what is HTML?

HTML is not a programming language; it is a markup language that defines the structure of your content. HTML consists of a series of elements, which you use to enclose, or wrap, different parts of the content to make it appear a certain way, or act a certain way. The enclosing tags can make a word or image hyperlink to somewhere else, can italicize words, can make the font bigger or smaller, and so on. For example, take the following line of content:

My dog is very excited

If we wanted the line to stand by itself, we could specify that it is a paragraph by enclosing it in paragraph tags:

<p>My dog is very excited</p>

Anatomy of an HTML element

Let's explore this paragraph element a bit further.

<p>My dog is very excited</p>

The main parts of our element are as follows:

The opening tag: This consists of the name of the element (in this case, p), wrapped in opening and closing angle brackets. This states where the element begins or start to take effect — in this case where the paragraph begins. The opening tag is shown in green.
The closing tag: This is the same as the opening tag, except that it includes a forward slash before the element name. This states where the element ends — in this case where the paragraph ends. Failing to add a closing tag is one of the standard beginner errors and can lead to strange results. The closing tag is shown in red.
The content: This is the content of the element, which in this case, is just text. The content is shown in between the opening and closing tags.
The element: The opening tag, the closing tag, and the content together comprise the element.

Elements can also have attributes. The attribute in the following example is shown in pink:

<p class="editor-note">My dog is very excited</p>

Attributes contain extra information about the element that you don't want to appear in the actual content. Here, class is the attribute name and editor-note is the attribute value. The class attribute allows you to give the element a non-unique identifier that can be used to target it (and any other elements with the same class value) with style information and other things.

An attribute should always have the following:

A space between it and the element name (or the previous attribute, if the element already has one or more attributes).
The attribute name followed by an equal sign.
The attribute value wrapped by opening and closing quotation marks.

Nesting elements

You can put elements inside other elements too — this is called nesting. If we wanted to state that our dog is very excited, we could wrap the word "very" in a <strong> element, which means that the word is to be strongly emphasized:

<p>My dog is <strong>very</strong>excited</p>

You do however need to make sure that your elements are properly nested. In the example above, we opened the <p> element first, then the <strong> element; therefore, we have to close the <strong> element first, then the <p> element. The following is incorrect:

<p>My dog is <strong>very excited</p></strong>

The elements have to open and close correctly so that they are clearly inside or outside one another. If they overlap as shown above, then your web browser will try to make the best guess at what you were trying to say, which can lead to unexpected results. So don't do it!

Empty elements

Some elements have no content and are called empty elements. Take the <img> element, for example:

<img src="images/happy-dog.png" alt="My happy dog">

This contains two attributes, but there is no closing </img> tag and no inner content. This is because an image element doesn't wrap content to affect it. Its purpose is to embed an image in the HTML page in the place it appears.

Anatomy of an HTML document

That wraps up the basics of individual HTML elements, but they aren't handy on their own. Now we'll look at how individual elements are combined to form an entire HTML page. Take a look at this example:

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>Happy Dog Page</title>
  </head>
  <body>
    <img src="images/happy-dog.png" alt="My happy dog">
  </body>
</html>

Here, we have the following:

<!DOCTYPE html> — doctype. It is a required preamble. In the mists of time, when HTML was young (around 1991/92), doctypes were meant to act as links to a set of rules that the HTML page had to follow to be considered good HTML, which could mean automatic error checking and other useful things. However these days, they don't do much and are basically just needed to make sure your document behaves correctly. That's all you need to know for now.
<html></html> — the <html> element. This element wraps all the content on the entire page and is sometimes known as the root element.
<head></head> — the <head> element. This element acts as a container for all the stuff you want to include on the HTML page that isn't the content you are showing to your page's viewers. This includes things like keywords and a page description that you want to appear in search results, CSS to style our content, character set declarations, and more.
<meta charset="UTF-8"> — This element sets the character set your document should use to UTF-8 which includes most characters from the vast majority of written languages. Essentially, it can now handle any textual content you might put on it. There is no reason not to set this and it can help avoid some problems later on.
<title></title> — the <title> element. This sets the title of your page, which is the title that appears in the browser tab the page is loaded in. It is also used to describe the page when you bookmark/favorite it.
<body></body> — the <body> element. This contains all the content that you want to show to web users when they visit your page, whether that's text, images, videos, games, playable audio tracks, or whatever else.

Images

Let's turn our attention to the <img> element again:

<img src="images/happy-dog.png" alt="My happy dog">

As we said before, it embeds an image into our page in the position it appears. It does this via the src (source) attribute, which contains the path to our image file.

We have also included an alt (alternative) attribute. In this attribute, you specify descriptive text for users who cannot see the image, possibly because of the following reasons:

They are visually impaired. Users with significant visual impairments often use tools called screen readers to read out the alt text to them.
Something has gone wrong causing the image not to display. For example, if the image path in the src attribute was incorrect, the image would fail to load and the browser would show the alt text instead.

The keywords for alt text are "descriptive text". The alt text you write should provide the reader with enough information to have a good idea of what the image conveys. In our happy dog example, our current text of "My happy dog" is no good at all. A much better alternative for our dog photo might be "A golden retriever running towards the camera in a grassy open field"

Marking up text

This section will cover some of the essential HTML elements you'll use for marking up the text.

Headings

Heading elements allow you to specify that certain parts of your content are headings — or subheadings. In the same way that a book has the main title, chapter titles, and subtitles, an HTML document can too. HTML contains 6 heading levels, <h1>–<h6>, although you'll commonly only use 3 to 4 at most:

<h1>My main title</h1>
<h2>My top level heading</h2>
<h3>My subheading</h3>
<h4>My sub-subheading</h4>

Paragraphs

As explained above, <p> elements are for containing paragraphs of text; you'll use these frequently when marking up regular text content:

<p>This is a single paragraph</p>

Lists

A lot of the web's content is lists and HTML has special elements for these. Marking up lists always consists of at least 2 elements. The most common list types are ordered and unordered lists:

Unordered lists are for lists where the order of the items doesn't matter, such as a shopping list. These are wrapped in a <ul> element.
Ordered lists are for lists where the order of the items does matter, such as a recipe. These are wrapped in an <ol> element.

Each item inside the lists is put inside an <li> (list item) element.

For example, if we wanted to turn the part of the following paragraph fragment into a list:

<p>My dog is a happy, silly, independent golden retriever</p>

We could modify the markup to this:

<p>My dog is a</p>
<ul>
  <li>happy</li>
  <li>silly</li>
  <li>independent</li>
</ul>
<p>golden retriever.</p>

Links

Links are very important — they are what makes the web a web! To add a link, we need to use a simple element — <a> — "a" being the short form for "anchor". To make text within a paragraph into a link, we follow these steps:

Choose some text. We choose "golden retriever".
Wrap the text in an <a> element, as shown below:
```
<a>golden retriever</a>
```
Give the <a> elment an href attribute, as shown below:
```
<a href="">golden retriever</a>
```
Fill in the value of this attribute with the web address that you want the link to link to:
```
<a href="https://en.wikipedia.org/wiki/Golden_Retriever">golden retriever</a>
```

You might get unexpected results if you omit the https:// or http:// part, called the protocol, at the beginning of the web address. After making a link, click it to make sure it is sending you where you wanted it to.

References

The content for this page is all borrowed from MDN's page on HTML basics. Please visit MDN if you have any questions.

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