HTML is a subset of SGML which is stand for Standard Generalized Mark-up Language. A mark-up language alters the presentation of the content of a document. The coded format language used for creating hypertext documents on the World Wide Web and controlling how Web Pages appear.

A generalized mark-up language can deal with many different document types, and a standard generalized mark-up language deals with all these documents in a standardized way. HTML presents data in a browser window in a multitude of shapes, sizes and colors, and provides extra features, such as forms and hyperlinks.

Dynamic HTML is a mixture of technologies to make dynamic Web pages. Most people mean by Dynamic HTML that HTML 4.0, Style Sheets and JavaScript combines DHTML. With DHTML we can alter the HTML page while it is being displayed, and provide animated content to the viewer.

JavaScript is a basic language as it adopts the core concepts of computer programming. JavaScript is an easy-to-use scripting programming language that can be embedded in the header of your web pages to add functionality and features. It can improve the dynamics and interactive features of your web page by allowing you to perform calculations, check forms, write interactive games, add special effects, customize graphics selections, create security passwords and more.

Advantages of JavaScript

• Speed:
  JavaScript is very fast because it is at the client-side. Any code functions can be run immediately instead of having to contact the server and wait for a response.
• Simplicity:
  It is relatively simple to learn and easy to implement.
• Versatility:
  JavaScript can interact easily with other languages and can be used in a vast variety of applications. Regardless of the file extension, JavaScript can be inserted into any web page. It can be used inside scripts written in other languages such as Perl and PHP.
• Server Load:
  It reduces server load as it resides on client-side