what is javascript?

I think that everyone have little knowledge about html.It is the abbreviation of Hypertext markup language.As you know it is just the template in order to make it an efficient one you have to add something to the template.It will be clear to those who have studied software engineering.So stop this thing and now lets us now start exploring what is meant by javascript.
Before jumping into any topic you should ask three ???
why is it needed?
How is it applied?
where is it applied?
ok I will answer these questions one by one.The html is just nothing but a static page.you can't do many things by using html alone.What I mean by that.You are creating a page that will be merely display the content without any additional features.The main purpose of javascript is to add interactivity to the user who are the resources for your site.
javascript=html +Business logic
what is meant by business logic.
Business logic is just nothing but how you want to model the content.
The special benefits of javascripts are
1)you can perform form validation in client side so that you can decrease the load on server side.
2)The important thing is you can dynamically create objects.Here objects are nothing but html elements.
The mother of javascript is Dom(Document object model).What I meant by that ?.You will understand later in detail.