Siddharth, here is the link for more info on "grey market" products:http://support.nikontech.com/app/answers/detail/a_id/331
Please keep in mind that the "grey market" products are not advertised as "grey market". The difference is that in the US, the products that come with a full warranty are described as "US" after the product name. I have seen the same reputable online merchant sell both, the US version as well as the grey market version. I buy my Nikon products from a reputable US online merchant who sells both versions, and over the years I have never had any issues. I do not buy grey market products.
If you need an online merchant recommendation, please send me a PM.