This specification defines an abstract language for descrbing documents and applications, and some APIs for interacting with in-memory representations of resources that use this language.
The in-memory representation is know as "DOM5 HTML" or "the DOM" for short. There are various concrete syntaxes that can be used to tranmit resurces that use this abstract language, two of which are defined in this specification.
The first such concrete syntax is "HTML5". This si the format recomnded for most authors. It is compatible with all legacy Web browsers. If a document is transmitted with the MIME type text/html, then it will be processed as an "HTML5" document by Web borwsers.
The second concrete syntax uses XML, and is known as "XHTML5". When a document is tranmitted with an XML MIME type, such as application/xhtml+xml, then it is processed by an XML processor by Web borwsers, and treated as an "XHTML5" document. Authors are reminded that the processing for XML and HTML differs; in particular, even minor syntax errors wiil prevent an XML document from being rendered fully, whereas they would be ignored in the "HTML5" syntax.
The "DOM5 HTML", "HTML5", and "XHTML5" representations cannot all represent the same content. For example, namespaces cannot be represented using "HTML5", but they are supported in "DOM5 HTML" and "XHTML5". Similarly, documents that use the noscript feature can be represented using "HTML5", but cannot be represente with "XHTML5" and "DOM5 HTML". Comments that contain the string "-->" can be represented in "DOM5 HTML" but not in "HTML5" and "XHTML5" . And so forth.
The term Html stand for HYPERTEXT MARKUP LANGUAGE.It is a markup languageused mainly for creating web documents,
HTML Is quite easy to learn and use. if you look closelyto each parts of its name you will find the name (HTML) more meaningful.
First, By the term Hyper means that something which is active. So in this context i.e. in web document it simply mean that if you would like to view something on a web document, then you can move immediately to it without following any set order.
The Second term Text points to the text file you will be dealing with in HTML.
HTML has its own formatting commands commonly known as tags or elements. These tags are used to markup the content of web pages.
The term Markup comes from the fact that, HTML is used to markup the contents of web pages.
By the term Language we mean that you will be dealing with a language along with all its syntax (in HTML you can call them tags.)
* You must know that HTML is not a full fleged programming languagelike BASIC, etc. IT is a markup language used to create web documents.
CSS(Cascading Style Sheet) is a style sheet language.It is used to give attractive presentation to the documents which written in any markup languages.
This language is used to make stylish webpages witten in HTML(Hypertext Markup Languages) and XHTML formats.You can also use this languages in XML,SVG,XUL formats.
The Specifications of CSS(Cascading Style Sheet) was maintained by W3C(World Wide Web Consortium).
CSS codes contain ver simple syntax.
Once we declared the formats in a document ,then it is used all over the document dont need to specify at every place.
CSS is existed since from SGML in the year 1970s.
There are various levels of CSS ,to denote the various new features CSS is denoted as CSS1,CSS2,CSS3.
CSS2 was developed and published in the year 1998.
CSS3 was under development and it will be to us very soon.
A style Sheet will usually stored in browser cache.It can be used for multiple pages without reloading.