What is Objects?
Objects provide a way to define specific pieces of data related to the item in question; these pieces are known as properties. In addition, these are supplemented by tasks that can be performed on or with that information, known as methods. Together properties and methods make up objects.
Because of the general nature of objects, specific instances can be created for each case where they are needed. For instance, a car object could then have several instances for Toyotas, Fords, and Volkswagens
 Window:-The window object provides methods and properties for dealing with the actual Navigator window, including objects for each frame.
 Location:-The location object provides properties and methods for working with the currently opened URL.
 History:-The history object provides information about the history list and enables limited interaction with the list.
 Document:-The document object is one of the most heavily used objects in the hierarchy. It contains objects, properties, and methods for working with document elements including forms, links and anchors.
 Forms  Anchors
String: - The string object enables programs to work with and manipulate strings of text, including extracting substrings and converting text to upper or lower case characters.
Math: - The Math object provides methods to perform trigonometric functions, such as sine and tangent, as well as general mathematical functions, such as square roots.
Date: - With the Date object, programs can work with the current date or create instances for specific dates. The object includes methods for calculating the difference between two dates and working with times.