6th_sem_web_unit1_bahagsgsgwgbapart1.pptx

RandyRandy ConnollyConnolly andand RicardoRicardo HoarHoar FundamentalsFundamentals ofof
Randy Connolly and Ricardo Hoar Fundamentals of Web Development
Textbook to be published by Pearson Ed in early 2
http://www.funwebdev.c
014
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Fundamentals of Web Development
Randy Connolly and Ricardo Hoar
© 2015 Pearson
http://www.funwebdev.com
HTML 1: Overview

Objectives
HTML Defined
and its History
HTML Syntax
Semantic Markup Structure of
HTML
Quick Tour of
HTML
1
3
5
2
4
6 HTML
Semantic Elements

Section 1 of 6
HTML DEFINED + ITS HISTORY

• ARPANET (Advanced Research Project Agency
Network)of the late 1960s by U.S DoD
(Department of Defence)
• jump quickly to the first public specification of
the HTML by Tim Berners-Lee in 1991
• HTML’s codification by the World-Wide Web
Consortium (better known as the W3C) in
1997.
• (W3C is the International standards
organization for www . Its task is to develop
protocols and guidelines that ensure long
term growth for the web).
Brief History of HTML
Did we mention that this will be brief?

HTML is defined as a markup language.
• A markup language is simply a way of annotating a
document in such a way to make the annotations
distinct from the text being annotated.
• The term comes from the days of print, when
editors would write instructions on manuscript
pages that might be revision instructions to the
author or copy editor.
HTML Syntax
What is a markup language?

Sample ad hoc markup

At its simplest, markup is a way to indicate
information about the content
• This “information about content” in HTML is
implemented via tags (aka elements).
• The markup in the previous slide consists of the red
text and the various circles and arrows on the one
page, and the little yellow sticky notes on the
other.
• HTML does the same thing but uses textual tags.
Markup
What is it again?

• The W3C is the main standards organization for the
World Wide Web.
• To promotes compatibility the W3C produces
recommendations (also called specifications).
• In 1998, the W3C turned its attention to a new
specification called XHTML 1.0, which was a version of
HTML that used stricter XML (Extensible Markup
Language) syntax rules.
• By 2009, the W3C stopped work on XHTML 2.0 and
instead adopted the HTML5.
What is the W3C?
Standards

HTML5 is the latest version of HTML and supports new markup
language functionalities such as multimedia, new tags and elements
as well as new API’s.
There are three main aims to HTML5:
• Specify unambiguously how browsers should deal with invalid
markup.
• Provide an open, non-proprietary programming framework (via
Javascript) for creating rich web applications.
• Be backwards compatible with the existing web.
HTML5
Three main aims

• While parts of the HTML5 are still being finalized,
all of the major browser manufacturers have at
least partially embraced HTML5.
• Certainly not all browsers and all versions support
every feature of HTML5.
• This is in fact by design. HTML in HTML5 is now a
living language: that is, it is a language that evolves
and develops over time.
• As such, every browser will support a gradually
increasing subset of HTML5 capabilities
HTML5
It evolves

HTML5 Support in Browsers

Section 2 of 6
HTML SYNTAX

HTML documents are composed of textual content
and HTML elements.
An HTML element can contain text, other elements, or
be empty. It is identified in the HTML document by
tags.
HTML elements can also contain attributes. An HTML
attribute is a name=value pair that provides more
information about the HTML element.
In XHTML, attribute values had to be enclosed in
quotes; in HTML5, the quotes are optional.
Elements and Attributes
More syntax

What HTML lets you do
▪ Insert images using the <img> tag
▪ Create links with the <a> tag
▪ Create lists with the <ul>, <ol> and
<li> tags
▪ Create headings with <H1>, <H2>,
…, <H6>
▪ Define metatdata with <meta> tag
▪ And much more…

Elements and Attributes

Nesting HTML elements
Often an HTML element will contain other HTML
elements.
In such a case, the container element is said to be a
parent of the contained, or child, element.
Any elements contained within the child are said to be
descendents of the parent element; likewise, any
given child element, may have a variety of ancestors.

Hierarchy of elements

Nesting HTML elements
In order to properly construct a hierarchy of elements,
your browser expects each HTML nested element to
be properly nested.
That is, a child’s ending tag must occur before its
parent’s ending tag.

Section 3 of 6
SEMANTIC MARKUP

Semantic markup refers to marking up a document
with information about the actual data structure
behind the information, rather than styling the
document with exclusively visual information.
Over the past decade, a strong and broad consensus
has grown around the belief that HTML documents
should only focus on the structure of the document.
Information about how the content should look when
it is displayed in the browser is best left to CSS
(Cascading Style Sheets).
Semantic Markup
What does it mean?

Semantic Markup
As a consequence, beginning HTML authors are often
counseled to create semantic HTML documents.
That is, an HTML document should not describe how
to visually present content, but only describe its
content’s structural semantics or meaning.

Structure
Structure is a vital way of communicating information
in paper and electronic documents.
All of the tags that we will examine in this
presentation are used to describe the basic structural
information in a document, such as articles, headings,
lists, paragraphs, links, images, navigation, footers,
and so on.

Eliminating presentation-oriented markup and writing
semantic HTML markup has a variety of important
advantages:
Maintainability. Semantic markup is easier to update and
change than web pages that contain a great deal of
presentation markup.
Faster. Semantic web pages are typically quicker to author
and faster to download.
Accessibility. Visiting a web page using voice reading
software can be a very frustrating experience if the site
does not use semantic markup.
Search engine optimization. Semantic markup provides
better instructions for search engines: it tells them what
things are important content on the site.
Semantic Markup
Its advantages

Section 4 of 6
STRUCTURE OF HTML

Simplest HTML document
The <title> element (Item ) is used to provide a broad description of the
content. The title is not displayed within the browser window. Instead, the
title is typically displayed by the browser in its window and/or tab.

A more complete document

Tells the browser (or any other client software that is
reading this HTML document) what type of document
it is about to process.
Notice that it does not indicate what version of HTML
is contained within the document: it only specifies
that it contains HTML.
DOCTYPE
(short for Document Type Definition)

HTML, Head, and Body
HTML5 does not require the use of the <html>,
<head>, and <body>.
However, in XHTML they were required, and most
web authors continue to use them.
The <html> element is sometimes called the root
element as it contains all the other HTML elements in
the document.

Head and Body
HTML pages are divided into two sections: the head
and the body, which correspond to the <head> and
<body> elements.
The head contains descriptive elements about the
document
The body contains content that will be displayed by
the browser.

You will notice that the <head> element contains a
variety of additional elements.
The first of these is the <meta> element. Our example
declares that the character encoding for the document
is UTF-8. (This covers almost all of the characters and
symbols in the world)
Inside the head
There are no brains

UTF-8 is an encoding system for Unicode. UTF stands for
“Unicode Transformation Format”
This encoding system can translate any Unicode character to a matching
Unicode binary string and can also translate the binary string back to a
Unicode character.
What is Unicode?
Unicode is an International character encoding standard that provides a
unique number for every character across languages and scripts, making
almost all characters accessible across platforms , programs and devices.
Unicode is a universal character set that defines all the characters needed
for writing the majority of living languages in use on computers.
Unicode aims to be (and already is) a superset of all other encoded
computer character sets.
The Unicode Standard covers (almost) all characters, punctuations, and
symbols in the world and enables processing, storage, and transport of
text independent of platform and language.

Our example specifies an external CSS style sheet file
that is used with this document.
It also references an external Javascript file.
Inside the head
No brains but metas, styles and javascripts

Section 5 of 6
QUICK TOUR OF HTML

Why a quick tour?
HTML5 contains many structural and presentation
elements – too many to completely cover in this
presentation.
Rather than comprehensively cover all these
elements, this presentation will provide a quick
overview of the most common elements.

Sample Document

HTML provides six levels of
heading (h1, h2, h3, …), with
the higher heading number
indicating a heading of less
importance.
Headings are an essential way
for document authors use to
show their readers the
structure of the document.
Headings
<h1>, <h2>, <h3>, etc

Headings
The browser has its
own default styling for
each heading level.
However, these are
easily modified and
customized via CSS.

In practice, specify a heading level that is semantically
accurate.
Do not choose a heading level because of its default
presentation
• e.g., choosing <h3> because you want your text to
be bold and 16pt
Rather, choose the heading level because it is
appropriate
• e.g., choosing <h3> because it is a third level
heading and not a primary or secondary heading
Headings
Be semantically accurate

Paragraphs are the most basic unit of text in an HTML
document.
Notice that the <p> tag is a container and can contain
HTML and other inline HTML elements
inline HTML elements refers to HTML elements that
do not cause a paragraph break but are part of the
regular “flow” of the text.
Paragraphs
<p>

This <div> tag is also a container element and is used
to create a logical grouping of content
• The <div> element has no intrinsic presentation.
• It is frequently used in contemporary CSS-based
layouts to mark out sections.
Divisions
<div>

HTML5 has a variety of new semantic elements (which
we will examine later) that can be used to reduce
somewhat the confusing mass of div within divs within
divs that is so typical of contemporary web design.
Using div elements
Can you say “div-tastic”

Links are created using the <a> element (the “a”
stands for anchor).
A link has two main parts: the destination and the
label.
Links
<a>

Types of Links
You can use the anchor element to create a wide range of
links:
• Links to external sites (or to individual resources
such as images or movies on an external site).
• Links to other pages or resources within the current
site.
• Links to other places within the current page.
• Links to particular locations on another page.
• Links that are instructions to the browser to start the
user’s email program.
• Links that are instructions to the browser to execute
a Javascript function.

Different link destinations

Links with the label “Click Here” were once a staple of
the web.
Today, such links are frowned upon, since:
• they do not tell users where the link will take them
• as a verb “click” is becoming increasingly inaccurate
when one takes into account the growth of mobile
browsers.
Instead, textual link labels should be descriptive.
“Click here to see the race results”
“Race Results” or “See Race Results”.
Link Text
Some guidance … or … don’t “Click Here”

When referencing a page or resource on an external
site, a full absolute reference is required: that is,
• the protocol (typically, http://),
• the domain name,
• any paths, and then finally
• the file name of the desired resource.
URL Absolute Referencing
For external resources

We also need to be able to successfully reference files
within our site.
This requires learning the syntax for so-called relative
referencing.
When referencing a resource that is on the same
server as your HTML document, then you can use
briefer relative referencing. If the URL does not
include the “http://” then the browser will request the
current server for the file.
URL Relative Referencing
An essential skill

If all the resources for the site reside within the same
directory (also referred to as a folder), then you can
reference those other resources simply via their
filename.
However, most real-world sites contain too many files
to put them all within a single directory.
For these situations, a relative pathname is required
along with the filename.
The pathname tells the browser where to locate the
file on the server.

Pathnames
Pathnames on the web follow Unix conventions.
• Forward slashes (“/”) are used to separate
directory names from each other and from file
names.
• Double-periods (“..”) are used to reference a
directory “above” the current one in the directory
tree.

Relative Link Type Example
Same Directory
To link to a file within the same
folder, simply use the file name.
To link toexample.html from
about.html(in Figure 2.18), use:
<a href="example.html">
Child Directory
To link to a file within a subdirectory,
use the name of the subdirectory and
a slash before the file name.
To link tologo.gif from about.html,
use:
<a href="images/logo.gif">
Grandchild/Descendant
Directory
To link to a file that is multiple
subdirectoriesbelow the current one,
construct the full path by including
each subdirectory name (separated
by slashes) before the file name.
To link tobackground.gif from
about.html,use:
<a
href="css/images/background.gif"
>
Parent/Ancestor Directory
Use “../” to reference a folderabove
the current one. If trying to reference
a file several levels above the current
one, simply string together multiple
To link toabout.html fromindex.html
in members,use:
<a href="../about.html">
To link toabout.html frombio.html,
use:
“../”.
<a href="../../about.html">

Sibling Directory
Use “../”to move up to the appropriate
level, and then use the same technique as
for child or grandchild directories.
To link to logo.gif from index.html in
members, use:
<a href="../images/about.html">
To link to background.gif from bio.html, use:
<a
href="../../css/images/background.gif">
Root Reference
An alternative approach for ancestor and
sibling references is to use the so-called
root reference approach. In this approach,
begin the reference with the root reference
(the “/”) and then use the same technique
as for child or grandchild directories. Note
that these will only work on the server!
That is, they will not work when you test it
out on your local machine.
To link to about.html from bio.html, use:
<a href="/about.html">
To link to background.gif from bio.html, use:
<a href="/images/background.gif">
Default Document
Web servers allow references to directory
names without file names. In such a case,
the web server will serve the default
document, which is usually a file called
index.html (apache) or default.html (IIS).
Again, this will only generally work on the
web server.
To link to index.html in members from
about.html, use either:
<a href="members">
Or
<a href="/members">

Inline elements do not disrupt the flow of text (i.e.,
cause a line break).
HTML5 defines over 30 of these elements.
e.g., <a>, <br>, <em>, <strong>
Inline Text Elements
Do not disrupt the flow

Images
While the <img> tag is the oldest method for
displaying an image, it is not the only way.
For purely decorative images, such as background
gradients and patterns, logos, border art, and so on, it
makes semantic sense to keep such images out of the
markup and in CSS where they more rightly belong.
But when the images are content, such as in the
images in a gallery or the image of a product in a
product details page, then the <img> tag is the
semantically appropriate approach.

Images

Unordered lists. Collections of items in no particular
order; these are by default rendered by the browser
as a bulleted list.
Ordered lists. Collections of items that have a set
order; these are by default rendered by the browser
as a numbered list.
Definition lists. Collection of name and definition
pairs. These tend to be used infrequently. Perhaps the
most common example would be a FAQ list.
Lists
HTML provides three types of lists

Lists

Character Entities
These are special characters for symbols for which
there is either no way easy way to type in via a
keyboard (such as the copyright symbol or accented
characters) or which have a reserved meaning in
HTML (for instance the “<” or “>” symbols).
They can be used in an HTML document by using the
entity name or the entity number.
e.g.,   and ©

6th_sem_web_unit1_bahagsgsgwgbapart1.pptx

Section 6 of 6
HTML SEMANTIC ELEMENTS

One substantial problem with modern, pre-HTML5
semantic markup:
most complex web sites are absolutely packed solid
with <div> elements.
Unfortunately, all these <div> elements can make the
resulting markup confusing and hard to modify.
Developers typically try to bring some sense and order
to the <div> chaos by using id or class names that
provide some clue as to their meaning.
HTML5 Semantic Elements
Why are they needed?

XHTML versus HTML5

Most web site pages have a recognizable header and
footer section.
Typically the header contains
• the site logo
• title (and perhaps additional subtitles or taglines)
• horizontal navigation links, and
• perhaps one or two horizontal banners.
Header and Footer
<header> <footer>

The typical footer contains less important material,
such as
• smaller text versions of the navigation,
• copyright notices,
• information about the site’s privacy policy, and
• perhaps twitter feeds or links to other social sites.
Header and Footer
<header> <footer>

Header and Footer
Both the HTML5 <header> and <footer> element can
be used not only for page headers and footers, they
can also be used for header and footer elements
within other HTML5 containers, such as <article> or
<section>.
<header>
<img src="logo.gif" alt="logo" />
<h1>Fundamentals of Web Development</h1>
...
</header>
<article>
<header>
<h2>HTML5 Semantic Structure Elements </h2>
<p>By <em>Randy Connolly</em></p>
<p><time>September 30, 2012</time></p>
</header>
...
</article>

The <hgroup> element can be used to group related
headings together within one container.
Heading Groups
<hgroup>
<header>
<hgroup>
<h1>Chapter Two: HTML 1</h1>
<h2>An Introduction</h2>
</hgroup>
</header>
<article>
<hgroup>
<h2>HTML5 Semantic Structure Elements </h2>
<h3>Overview</h3>
</hgroup>
</article>

The <nav> element represents a section of a page that
contains links to other pages or to other parts within
the same page.
Like the other new HTML5 semantic elements, the
browser does not apply any special presentation to
the <nav> element.
The <nav> element was intended to be used for major
navigation blocks, presumably the global and
secondary navigation systems.
Navigation
<nav>

Navigation
<header>
<img src="logo.gif" alt="logo" />
<h1>Fundamentals of Web Development</h1>
<nav role="navigation">
<ul>
<li><a href="index.html">Home</a></li>
<li><a href="about.html">About Us</a></li>
<li><a href="browse.html">Browse</a></li>
</ul>
</nav>
</header>

The <article> element represents a section of content
that forms an independent part of a document or site;
for example, a magazine or newspaper article, or a
blog entry.
The <section> element represents a section of a
document, typically with a title or heading.
Articles and Sections
<article> <section>

Articles and Sections
According to the W3C, <section> is a much broader
element, while the <article> element is to be used for
blocks of content that could potentially be read or
consumed independently of the other content on the
page.

The WHATWG specification warns readers that the
<section> element is not a generic container element.
HTML already has the <div> element for such uses.
When an element is needed only for styling purposes
or as a convenience for scripting, it makes sense to use
the <div> element instead.
Another way to help you decide whether or not to use
the <section> element is to ask yourself if it is
appropriate for the element's contents to be listed
explicitly in the document's outline.
If so, then use a <section>; otherwise use a <div>.
Sections versus Divs
How to decide which to use

The W3C Recommendation indicates that the <figure>
element can be used not just for images but for any
type of essential content that could be moved to a
different location in the page or document and the
rest of the document would still make sense.
Figure and Figure Captions
<figure> <figcaption>

The <figure> element should not be used to wrap
every image.
For instance, it makes no sense to wrap the site logo
or non-essential images such as banner ads and
graphical embellishments within <figure> elements.
Instead, only use the <figure> element for
circumstances where the image (or other content) has
a caption and where the figure is essential to the
content but its position on the page is relatively
unimportant.
Note however …

The <aside> element is similar to the <figure> element
in that it is used for marking up content that is
separate from the main content on the page.
But while the <figure> element was used to indicate
important information whose location on the page is
somewhat unimportant, the <aside> element
“represents a section of a page that consists of
content that is tangentially related to the content
around the aside element.”
The <aside> element could thus be used for sidebars,
pull quotes, groups of advertising images, or any other
grouping of non-essential elements.
Aside
<aside>

What You’ve Learned
HTML Defined
and its History
HTML Syntax
Semantic Markup Structure of
HTML
Quick Tour of
HTML
HTML
Semantic
Elements
1
3
5
2
4
6

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