HTML stands for Hyper Text Markup Language. It is used by Internet browsers to display web content
in a structured manner. In this module, we focus on HTML4 (HTML 4.01) version of HTML. We would
touch upon HTML5 as and when needed. However, a detailed discussion of HTML5 is out of the scope
for this module.
HTML is a tag-based language and uses tags to identify its elements. Authoring an HTML document
is simply a matter of putting content within the relevant tags. For example, if we have to
create a paragraph for some text, we can use the <p> tag to mark the start of the paragraph
add the text, and then use the </p> to end the paragraph. In fact, the entire HTML document itself
sits within two tags -- it begins with <html> tag and once the entire document is done, it
ends with the </html> tag.
Like the above examples of <p> and <html>, majority of HTML elements are identified as a pair of
tags: the first tag (the opening tag)
marks the beginning of an element and the second tag (the closing tag) marks the ends of that
element. However, there are a handful of
HTML elements that work just fine even with one single tag. These elements do not enclose any content and
hence, all they need is the opening tag. Since they do not enclose any content,
they are also known as empty elements, void elements, or singleton elements.
In terms of structure, an HTML document has two prominent tags: head and body. The
head section is identified by the <head> and </head> tag-pair and contains meta-information of the HTML
page (like say, the title of the page). The body section is identified by the <body> and </body>
tag-pair and encloses the actual content of the HTML page. However, these head and body tags are
optional. Thus, it is
possible to have a valid HTML page that does not contain any these
four tags: <head>, </head>, <body>, and </body>!
While content sits within tags that identify HTML elements, tags can additionally have
specific modifiers. These modifiers are called attributes. Both tag names and attribute names are
case-insensitive. Thus, if we were to write the head element, then both <HEAD> and <head>
would mean the same thing. Same is true for attributes.
HTML also provides elements and attributes that focus on accessibility. These constructs help us
render content for
non-visual readers like non-graphic display terminals, speech synthesizers etc. As we go along,
we would make a note as and when we touch upon these elements. When we write an HTML document, it
is important that we pay attention to these elements since they would make the document more
widely acceptable.
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