The Document Object Model (DOM), one of the most powerful tools available to a web developer.

DOM hierarchy,

Window Object:

The window object is at the top of the DOM hierarchy.The window object contains properties that apply to the entire window.The common DOM methods for window object’s are,

focus(),resizeby(a,b)

Navigator Object:

This object provides information about the browser being used.Common Uses are,

document.write(navigator.appName)
document.write(navigator.appVersion)
document.write(navigator.platform)
document.write(navigator.cpuClass)

Document Object:

      Document object contains properties for the current page
loaded in the window.Common methods are,

document.write()
document.open()
document.fileCreatedDate()

History Object:

      The history object is also a property of the window object.
It contains properties of the URLs the user has previously visited.The
Common methods/Properties for history object are

Current,Previous,next

Location Object:

       The location object contains properties of the current URL.

document.write(location.href)
document.write(window.location.protocol)

I felt now you got better understanding of document object model.

Happy Programming!.