Google typically obeys robots.txt and will not index you at all if you follow Ozzy's instructions on that.

I would be willing to bet you could add this to the very top of your .htaccess file, and it should do it also,

What actually are you wanting to do? Because if you have hidden forums, threads, or any other areas of your site that require login to view, google and all other spiders, cannot index them. Because they cannot see them.

If you block spiders completely or command 'no index nofollow' you will not show up in searches and makes it difficult for people to ever find your site.

With Bop5's mod here, you can also hide individual threads from the unregistered/not logged in usergroup and this includes all spiders. This hides threads you designate regardless of what forum they are in, or of existing permissions.

aahh ok, Its perfect then. This is my doubt. Further I will install the mod...

On the future,within a time If I unninstall this mod and I want index, there is any problem?

If you install the mod you will likely be blacklisted by the legitimate search engines. Install it ONLY if this is what you want.

very interesting...

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ok, thank you ozzy and Maxx. GOOD HELP! :)

Not a problem, glad to help. :)

I should rephrase this. The mod alone won't get you blacklisted and in fact it is one of the better anti-spam tools around. It's the LIST you use with it - the one I linked to is for legitimate spiders for identification in "Who's Online" only. Using that LIST with this mod might lead to search engine blacklists. Follow the link in my signature for the right definitions list, to use with the "Ban Spiders" Mod.

Also, if you want to know if something will be indexed by a robot, view your site as a guest, and what ever you see while not logged in, is what the robots will see.