I am new in creating SharePoint apps. I have created SharePoint hosted app. It is deployed properly. But default master page is not applied to it. It just showing plain HTML page. Your help will be appriciable. Thanks
You can't really get the SharePoint master page, but you can inherit the look and feel of SharePoint by using the 'Chrome Control'.
Here's a walkthrough:
By default your app will use the app.master regardless of what the host is using. Microsoft at this point expects the host is using its default master pages and your app will loom similar with app.master or you can use chrome control to get a similar look but modify as required for the App. Note this is still independent of the host. Microsoft has posted some UX guidelines on MSDN for ShatePoint apps.