Guide to html coding

Introduction to HTML

At its heart, HTML is a language made up of elements, which can be applied to pieces of text to give them different meaning in a document (Is it a paragraph? Is it a bulleted list? Is it part of a table?), structure a document into logical sections (Does it have a header? Three columns of content? A navigation menu?), and embed content such as images and videos into a page. This module will introduce the first two of these and introduce fundamental concepts and syntax you need to know to understand HTML.

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Prerequisites

Before starting this module, you don’t need any previous HTML knowledge, but you should have at least basic familiarity with using computers and using the web passively (i.e., just looking at it and consuming content). You should have a basic work environment set up (as detailed in Installing basic software), and understand how to create and manage files (as detailed in Dealing with files). Both are parts of our Getting started with the web complete beginner’s module.

Note: If you are working on a computer/tablet/other device where you don’t have the ability to create your own files, you could try out (most of) the code examples in an online coding program such as JSBin or Glitch.

Guides

This module contains the following articles, which will take you through all the basic theory of HTML and provide ample opportunity for you to test out some skills.

Covers the absolute basics of HTML, to get you started — we define elements, attributes, and other important terms, and show where they fit in the language. We also show how a typical HTML page is structured and how an HTML element is structured, and explain other important basic language features. Along the way, we’ll play with some HTML to get you interested!

The head of an HTML document is the part that is not displayed in the web browser when the page is loaded. It contains information such as the page , links to CSS (if you want to style your HTML content with CSS), links to custom favicons, and metadata (data about the HTML, such as who wrote it, and important keywords that describe the document).

One of HTML’s main jobs is to give text meaning (also known as semantics), so that the browser knows how to display it correctly. This article looks at how to use HTML to break up a block of text into a structure of headings and paragraphs, add emphasis/importance to words, create lists, and more.

Hyperlinks are really important — they are what makes the web a web. This article shows the syntax required to make a link and discusses best practices for links.

There are many other elements in HTML for formatting text that we didn’t get to in the HTML text fundamentals article. The elements here are less well-known, but still useful to know about. In this article, you’ll learn about marking up quotations, description lists, computer code and other related text, subscript and superscript, contact information, and more.

As well as defining individual parts of your page (such as «a paragraph» or «an image»), HTML is also used to define areas of your website (such as «the header», «the navigation menu», or «the main content column»). This article looks into how to plan a basic website structure and how to write the HTML to represent this structure.

Writing HTML is fine, but what if something goes wrong, and you can’t work out where the error in the code is? This article will introduce you to some tools that can help.

Assessments

The following assessments will test your understanding of the HTML basics covered in the guides above.

We all learn to write a letter sooner or later; it is also a useful example to test out text formatting skills. In this assessment, you’ll be given a letter to mark up.

This assessment tests your ability to use HTML to structure a simple page of content, containing a header, a footer, a navigation menu, main content, and a sidebar.

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HTML Introduction

HTML is the standard markup language for creating Web pages.

What is HTML?

• HTML stands for Hyper Text Markup Language
• HTML is the standard markup language for creating Web pages
• HTML describes the structure of a Web page
• HTML consists of a series of elements
• HTML elements tell the browser how to display the content
• HTML elements label pieces of content such as «this is a heading», «this is a paragraph», «this is a link», etc.

A Simple HTML Document

Example

My First Heading

My first paragraph.

Example Explained

• The declaration defines that this document is an HTML5 document
• The element is the root element of an HTML page
• The element contains meta information about the HTML page
• The element specifies a title for the HTML page (which is shown in the browser’s title bar or in the page’s tab)
• The element defines the document’s body, and is a container for all the visible contents, such as headings, paragraphs, images, hyperlinks, tables, lists, etc.
• The element defines a large heading
• The

  element defines a paragraph

What is an HTML Element?

An HTML element is defined by a start tag, some content, and an end tag:

The HTML element is everything from the start tag to the end tag:

Note: Some HTML elements have no content (like the
element). These elements are called empty elements. Empty elements do not have an end tag!

Web Browsers

The purpose of a web browser (Chrome, Edge, Firefox, Safari) is to read HTML documents and display them correctly.

A browser does not display the HTML tags, but uses them to determine how to display the document:

HTML Page Structure

Below is a visualization of an HTML page structure:

This is a heading

This is another paragraph.

Note: The content inside the section will be displayed in a browser. The content inside the element will be shown in the browser’s title bar or in the page’s tab.

HTML History

Since the early days of the World Wide Web, there have been many versions of HTML:

Year	Version
1989	Tim Berners-Lee invented www
1991	Tim Berners-Lee invented HTML
1993	Dave Raggett drafted HTML+
1995	HTML Working Group defined HTML 2.0
1997	W3C Recommendation: HTML 3.2
1999	W3C Recommendation: HTML 4.01
2000	W3C Recommendation: XHTML 1.0
2008	WHATWG HTML5 First Public Draft
2012	WHATWG HTML5 Living Standard
2014	W3C Recommendation: HTML5
2016	W3C Candidate Recommendation: HTML 5.1
2017	W3C Recommendation: HTML5.1 2nd Edition
2017	W3C Recommendation: HTML5.2

This tutorial follows the latest HTML5 standard.

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HTML Style Guide

A consistent, clean, and tidy HTML code makes it easier for others to read and understand your code.

Here are some guidelines and tips for creating good HTML code.

Always Declare Document Type

Always declare the document type as the first line in your document.

The correct document type for HTML is:

Use Lowercase Element Names

HTML allows mixing uppercase and lowercase letters in element names.

However, we recommend using lowercase element names, because:

• Mixing uppercase and lowercase names looks bad
• Developers normally use lowercase names
• Lowercase looks cleaner
• Lowercase is easier to write

Good:

Bad:

Close All HTML Elements

In HTML, you do not have to close all elements (for example the

element).

However, we strongly recommend closing all HTML elements, like this:

Good:

Bad:

This is a paragraph.

This is a paragraph.

Use Lowercase Attribute Names

HTML allows mixing uppercase and lowercase letters in attribute names.

However, we recommend using lowercase attribute names, because:

• Mixing uppercase and lowercase names looks bad
• Developers normally use lowercase names
• Lowercase looks cleaner
• Lowercase is easier to write

Good:

Bad:

Always Quote Attribute Values

HTML allows attribute values without quotes.

However, we recommend quoting attribute values, because:

• Developers normally quote attribute values
• Quoted values are easier to read
• You MUST use quotes if the value contains spaces

Good:

This will not work, because the value contains spaces:

Always Specify alt, width, and height for Images

Always specify the alt attribute for images. This attribute is important if the image for some reason cannot be displayed.

Also, always define the width and height of images. This reduces flickering, because the browser can reserve space for the image before loading.

Good:

Bad:

Spaces and Equal Signs

HTML allows spaces around equal signs. But space-less is easier to read and groups entities better together.

Good:

Bad:

Avoid Long Code Lines

When using an HTML editor, it is NOT convenient to scroll right and left to read the HTML code.

Try to avoid too long code lines.

Blank Lines and Indentation

Do not add blank lines, spaces, or indentations without a reason.

For readability, add blank lines to separate large or logical code blocks.

For readability, add two spaces of indentation. Do not use the tab key.

Good:

Famous Cities

Tokyo

Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the most populous metropolitan area in the world.

London

London is the capital city of England. It is the most populous city in the United Kingdom.

Paris

Paris is the capital of France. The Paris area is one of the largest population centers in Europe.

Bad:

Famous Cities

Tokyo

Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the most populous metropolitan area in the world.

London

London is the capital city of England. It is the most populous city in the United Kingdom.

Paris

Paris is the capital of France. The Paris area is one of the largest population centers in Europe.

Good Table Example:

Good List Example:

Never Skip the Element

The element is required in HTML.

The contents of a page title is very important for search engine optimization (SEO)! The page title is used by search engine algorithms to decide the order when listing pages in search results.

• defines a title in the browser toolbar
• provides a title for the page when it is added to favorites
• displays a title for the page in search-engine results

So, try to make the title as accurate and meaningful as possible:

Omitting and ?

An HTML page will validate without the and tags:

Example

This is a heading

This is a paragraph.

However, we strongly recommend to always add the and tags!

Omitting can produce errors in older browsers.

Omitting and can also crash DOM and XML software.

Omitting ?

The HTML tag can also be omitted.

Browsers will add all elements before , to a default element.

Example

This is a heading

This is a paragraph.

However, we recommend using the tag.

Close Empty HTML Elements?

In HTML, it is optional to close empty elements.

Allowed:

Also Allowed:

If you expect XML/XHTML software to access your page, keep the closing slash (/), because it is required in XML and XHTML.

Add the lang Attribute

You should always include the lang attribute inside the tag, to declare the language of the Web page. This is meant to assist search engines and browsers.

Example

This is a heading

This is a paragraph.

Meta Data

To ensure proper interpretation and correct search engine indexing, both the language and the character encoding charset«> should be defined as early as possible in an HTML document:

Setting The Viewport

The viewport is the user’s visible area of a web page. It varies with the device — it will be smaller on a mobile phone than on a computer screen.

You should include the following element in all your web pages:

This gives the browser instructions on how to control the page’s dimensions and scaling.

The width=device-width part sets the width of the page to follow the screen-width of the device (which will vary depending on the device).

The initial-scale=1.0 part sets the initial zoom level when the page is first loaded by the browser.

Here is an example of a web page without the viewport meta tag, and the same web page with the viewport meta tag:

Tip: If you are browsing this page with a phone or a tablet, you can click on the two links below to see the difference.

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