Thank you Pradeep. Great information. That would certainly help others as it did to me. I would like to inform you that Please try and edit 2nd paragraph under Spiders or Crawlers. There is repetition there which makes the great article a little clumsy and remove " Meta Tag is" in the very next paragraph if you can. I would like to know about search logic of Social networking sites like Facebook or Myspace from you. because you seem to have great knowledge about search engine and their logic.