Client-side Scripting Environment (Browsers and Editors)
The World Wide Web (WWW) began as a text-only medium-the first browsers didn't even support images within web pages.
If you know how to use HTML (Hypertext Markup Language) to create a web document, you've already worked with one computer language. You use HTML tags to describe how you want your document formatted, and the browser obeys your commands and shows the formatted document to the user.
Because HTML is a simple text markup language, it can't respond to the user, make decisions, or automate repetitive tasks. Interactive tasks such as these require a more sophisticated language: a programming language, or a scripting language.
Although many programming languages are complex, scripting languages are generally simple. They have a simple syntax, can perform tasks with a minimum of commands, and are easy to learn. Web scripting languages enable you to combine scripting with HTML to create interactive web pages.
Next : Scripts and Programs