Question:What do you mean by DOM? Write its properties. 

The Document Object Model (DOM) is a cross-platform and language-independent convention for representing and interacting with objects in HTML, XHTML and XML documents.

Some of Document Properties:
a. AlinkColor
b. Anchors[array]
c. BgColor
d. Cookie
e. Domain
g. Forms[array]
h. Images[array]
i. LinkColor
j. Links[array]
k. Location
l. Title

Question:What is history object? Write methods of it. 

history object: 1. The history object is a property of the window object. It has a single property name length. 
2. The history object contains the URLs visited by the user (within a browser window).

functions: 1. back() - Loads the previous URL in the history list.
2. forward() - Loads the next URL in the history list.
3. go() - Loads a specific URL from the history list.