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HTML
HyperText Markup Language (HTML) is a markup language used to construct online documents and is the foundation of most websites today. A markup language like HTML allows us to:
- Create links to other documents
- Structure the content in our document
- Attribute context and meaning to the content of our document
An HTML document has two aspects to it. It contains structured information (Markup), and text-links (HyperText) to other documents. We structure our pages using HTML elements. They are constructs of the language providing structure and meaning in our document for the browser and linking to other documents across the internet.
The first publicly available description of HTML was a document called "HTML Tags", first mentioned on the Internet in late 1991 by Tim Berners-Lee, who is widely credited with the invention of html.
The internet was originally created to store and present static (unchanging) documents. The aspects of HTML discussed above were seen perfectly in these documents which lacked all design and styling. They presented structured information that contained links to other documents.
HTML5 is the latest version, or specification, of HTML. The World Wide Web Consortium (W3C) is the organization responsible for developing standards for the World Wide Web, including those for HTML. As web pages and web applications grow more complex, W3C updates HTML's standards.
HTML5 introduced a host of semantic elements. As discussed, HTML provides meaning to our document, however it wasn't until HTML5's introduction of semantic elements that its potential was realized.
A simple example of an HTML Document
<!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
</head>
<body>
<h1>My First Heading</h1>
<p>My first paragraph.</p>
</body>
</html>
!DOCTYPE html: Defines this document to be HTML5
html: The root element of an HTML page
head: This element contains meta information about the document
title: This element specifies a title for the document
body: This element contains the visible page content
h1: This element defines a large heading
p: This element defines a paragraph
HTML Tags
HTML tags are element names surrounded by angle brackets:
<tagname> here is the content.. </tagname>
HTML tags normally come in pairs like <h1>and </h1>
The first tag in a pair is the start tag, the second tag is the end tag
The end tag is written like the start tag, but with a forward slash inserted before the tag name
HTML Versions
Since the early days of the web, there have been many versions of HTML:
| Version | Year |
|---|---|
| HTML | 1991 |
| HTML 2.0 | 1995 |
| HTML 3.2 | 1997 |
| HTML 4.01 | 1999 |
| XHTML | 2000 |
| HTML5 | 2014 |
HTML Elements
The extent of an element is indicated by a pair of tags: a "start tag" <p> and "end tag" </p>. The text content of the element, if any, is placed between these tags.
Tags may also enclose further tag markup between the start and end, including a mixture of tags and text. This indicates further (nested) elements, as children of the parent element.
The start tag may also include attributes within the tag. These indicate other information, such as identifiers for sections within the document, identifiers used to bind style information to the presentation of the document, and for some tags such as the <img> used to embed images, the reference to the image resource.
Some elements, such as the line break <br> or <br/>, do not permit any embedded content, either text or further tags. These require only a single empty tag (start tag) and do not use an end tag.
Element examples
Header of the HTML document:
<head>...</head>
The <title>...</title> element is one element normally included in the head. For example:
<head>
<title>The Title</title>
</head>
Headings
HTML headings are defined with the <h1> to <h6> tags:
<h1>Heading 1</h1>
<h2>Heading 2</h2>
<h3>Heading 3</h3>
<h4>Heading 4</h4>
<h5>Heading 5</h5>
<h6>Heading 6</h6>
Paragraphs
<p>Paragraph 1</p>
<p>Paragraph 2</p>
Line Breaks
<br/>
The difference between <br/> and <p> is that br breaks a line without altering the semantic structure of the page, whereas p sections the page into paragraphs. Note also that br is an empty element in that, although it may have attributes, it can take no content and it may not have an end tag.
<p>This is a paragraph <br> with <br> line breaks</p>
Anchor/Links
To create a link the <a> tag is used. The href attribute holds the URL address of the link.
<a href="https://www.youtube.com">A link to Youtube!</a>
Inputs
There are many possible ways a user can give input/s like:
<input type="text" /> <!-- This is for text input -->
<input type="file" /> <!-- This is for uploading files -->
<input type="checkbox" /> <!-- This is for checkboxes -->
Comments
<!-- This is a comment -->
Comments can help in the understanding of the markup and do not display in the webpage.