why no .html in the end of URL

[lazycat]

Hi guys,

 

i am just wodnering why there is no .html in the end of the URL

such as my log in page URL is as below,

 

http://www.mystore.com/authentication

 

But i want get the URL as

http://www.ak2i3ds.com/authentication.html

 

can anyone give me a solution on that ?

 

Highly appreciate on that. Thanks a lot.