Google Indexing: Check the link indexed by google or not

Hi,

Today I found a friend of mine having problem with a page of his website. He was not able to encounter that weather the specific page of his website has indexed or not.

First of all lets talk something technical.There are crawlers that crawls all the links in your website and indexing is done but sometimes due to some errors the indexing is not done.Crawling and Indexing are the important as far as SEO is concerned.
Now how to check weather you page or link is indexed or not.
Go to the google search box and type "info:your link" and hit enter, If it shows result that means your page or link has been indexed and if it shows error that means your page or link is not indexed.

And if you need more details about indexing the visit : Searchengineland